diff --git a/api/cosmos/nft/v1beta1/event.pulsar.go b/api/cosmos/nft/v1beta1/event.pulsar.go
index e67deb473..16b7a6c26 100644
--- a/api/cosmos/nft/v1beta1/event.pulsar.go
+++ b/api/cosmos/nft/v1beta1/event.pulsar.go
@@ -1739,9 +1739,13 @@ type EventSend struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
-	ClassId  string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Id       string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
-	Sender   string `protobuf:"bytes,3,opt,name=sender,proto3" json:"sender,omitempty"`
+	// class_id associated with the nft
+	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
+	// id is a unique identifier of the nft
+	Id string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
+	// sender is the address of the owner of nft
+	Sender string `protobuf:"bytes,3,opt,name=sender,proto3" json:"sender,omitempty"`
+	// receiver is the receiver address of nft
 	Receiver string `protobuf:"bytes,4,opt,name=receiver,proto3" json:"receiver,omitempty"`
 }
 
@@ -1799,9 +1803,12 @@ type EventMint struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Id      string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
-	Owner   string `protobuf:"bytes,3,opt,name=owner,proto3" json:"owner,omitempty"`
+	// id is a unique identifier of the nft
+	Id string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
+	// owner is the owner address of the nft
+	Owner string `protobuf:"bytes,3,opt,name=owner,proto3" json:"owner,omitempty"`
 }
 
 func (x *EventMint) Reset() {
@@ -1851,9 +1858,12 @@ type EventBurn struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Id      string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
-	Owner   string `protobuf:"bytes,3,opt,name=owner,proto3" json:"owner,omitempty"`
+	// id is a unique identifier of the nft
+	Id string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
+	// owner is the owner address of the nft
+	Owner string `protobuf:"bytes,3,opt,name=owner,proto3" json:"owner,omitempty"`
 }
 
 func (x *EventBurn) Reset() {
diff --git a/api/cosmos/nft/v1beta1/genesis.pulsar.go b/api/cosmos/nft/v1beta1/genesis.pulsar.go
index 98980a0e4..c2a085a30 100644
--- a/api/cosmos/nft/v1beta1/genesis.pulsar.go
+++ b/api/cosmos/nft/v1beta1/genesis.pulsar.go
@@ -1223,6 +1223,7 @@ type GenesisState struct {
 
 	// class defines the class of the nft type.
 	Classes []*Class `protobuf:"bytes,1,rep,name=classes,proto3" json:"classes,omitempty"`
+	// entry defines all nft owned by a person.
 	Entries []*Entry `protobuf:"bytes,2,rep,name=entries,proto3" json:"entries,omitempty"`
 }
 
diff --git a/api/cosmos/nft/v1beta1/query.pulsar.go b/api/cosmos/nft/v1beta1/query.pulsar.go
index f045f7094..cfcb7d51b 100644
--- a/api/cosmos/nft/v1beta1/query.pulsar.go
+++ b/api/cosmos/nft/v1beta1/query.pulsar.go
@@ -6567,8 +6567,10 @@ type QueryBalanceRequest struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Owner   string `protobuf:"bytes,2,opt,name=owner,proto3" json:"owner,omitempty"`
+	// owner is the owner address of the nft
+	Owner string `protobuf:"bytes,2,opt,name=owner,proto3" json:"owner,omitempty"`
 }
 
 func (x *QueryBalanceRequest) Reset() {
@@ -6611,6 +6613,7 @@ type QueryBalanceResponse struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
+	// amount is the number of all NFTs of a given class owned by the owner
 	Amount uint64 `protobuf:"varint,1,opt,name=amount,proto3" json:"amount,omitempty"`
 }
 
@@ -6647,8 +6650,10 @@ type QueryOwnerRequest struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Id      string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
+	// id is a unique identifier of the NFT
+	Id string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
 }
 
 func (x *QueryOwnerRequest) Reset() {
@@ -6691,6 +6696,7 @@ type QueryOwnerResponse struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
+	// owner is the owner address of the nft
 	Owner string `protobuf:"bytes,1,opt,name=owner,proto3" json:"owner,omitempty"`
 }
 
@@ -6727,6 +6733,7 @@ type QuerySupplyRequest struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
 }
 
@@ -6763,6 +6770,7 @@ type QuerySupplyResponse struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
+	// amount is the number of all NFTs from the given class
 	Amount uint64 `protobuf:"varint,1,opt,name=amount,proto3" json:"amount,omitempty"`
 }
 
@@ -6799,8 +6807,11 @@ type QueryNFTsRequest struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
-	ClassId    string               `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Owner      string               `protobuf:"bytes,2,opt,name=owner,proto3" json:"owner,omitempty"`
+	// class_id associated with the nft
+	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
+	// owner is the owner address of the nft
+	Owner string `protobuf:"bytes,2,opt,name=owner,proto3" json:"owner,omitempty"`
+	// pagination defines an optional pagination for the request.
 	Pagination *v1beta1.PageRequest `protobuf:"bytes,3,opt,name=pagination,proto3" json:"pagination,omitempty"`
 }
 
@@ -6851,7 +6862,9 @@ type QueryNFTsResponse struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
-	Nfts       []*NFT                `protobuf:"bytes,1,rep,name=nfts,proto3" json:"nfts,omitempty"`
+	// NFT defines the NFT
+	Nfts []*NFT `protobuf:"bytes,1,rep,name=nfts,proto3" json:"nfts,omitempty"`
+	// pagination defines the pagination in the response.
 	Pagination *v1beta1.PageResponse `protobuf:"bytes,2,opt,name=pagination,proto3" json:"pagination,omitempty"`
 }
 
@@ -6895,8 +6908,10 @@ type QueryNFTRequest struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Id      string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
+	// id is a unique identifier of the NFT
+	Id string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
 }
 
 func (x *QueryNFTRequest) Reset() {
@@ -6939,6 +6954,7 @@ type QueryNFTResponse struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
+	// owner is the owner address of the nft
 	Nft *NFT `protobuf:"bytes,1,opt,name=nft,proto3" json:"nft,omitempty"`
 }
 
@@ -6975,6 +6991,7 @@ type QueryClassRequest struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
 }
 
@@ -7011,6 +7028,7 @@ type QueryClassResponse struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
+	// class defines the class of the nft type.
 	Class *Class `protobuf:"bytes,1,opt,name=class,proto3" json:"class,omitempty"`
 }
 
@@ -7084,7 +7102,9 @@ type QueryClassesResponse struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
-	Classes    []*Class              `protobuf:"bytes,1,rep,name=classes,proto3" json:"classes,omitempty"`
+	// class defines the class of the nft type.
+	Classes []*Class `protobuf:"bytes,1,rep,name=classes,proto3" json:"classes,omitempty"`
+	// pagination defines the pagination in the response.
 	Pagination *v1beta1.PageResponse `protobuf:"bytes,2,opt,name=pagination,proto3" json:"pagination,omitempty"`
 }
 
diff --git a/proto/cosmos/crisis/v1beta1/tx.proto b/proto/cosmos/crisis/v1beta1/tx.proto
index fc9a3fcee..80663e35a 100644
--- a/proto/cosmos/crisis/v1beta1/tx.proto
+++ b/proto/cosmos/crisis/v1beta1/tx.proto
@@ -32,13 +32,13 @@ message MsgVerifyInvariant {
   option (gogoproto.goproto_getters) = false;
 
   // sender is the account address of private key to send coins to fee collector account.
-  string sender                = 1 [(cosmos_proto.scalar) = "cosmos.AddressString"];
-  
+  string sender = 1 [(cosmos_proto.scalar) = "cosmos.AddressString"];
+
   // name of the invariant module.
   string invariant_module_name = 2;
 
   // invariant_route is the msg's invariant route.
-  string invariant_route       = 3;
+  string invariant_route = 3;
 }
 
 // MsgVerifyInvariantResponse defines the Msg/VerifyInvariant response type.
diff --git a/proto/cosmos/nft/v1beta1/event.proto b/proto/cosmos/nft/v1beta1/event.proto
index 96964f08a..2f6d5a0d2 100644
--- a/proto/cosmos/nft/v1beta1/event.proto
+++ b/proto/cosmos/nft/v1beta1/event.proto
@@ -5,22 +5,39 @@ option go_package = "github.com/cosmos/cosmos-sdk/x/nft";
 
 // EventSend is emitted on Msg/Send
 message EventSend {
+  // class_id associated with the nft
   string class_id = 1;
-  string id       = 2;
-  string sender   = 3;
+
+  // id is a unique identifier of the nft
+  string id = 2;
+
+  // sender is the address of the owner of nft
+  string sender = 3;
+
+  // receiver is the receiver address of nft
   string receiver = 4;
 }
 
 // EventMint is emitted on Mint
 message EventMint {
+  // class_id associated with the nft
   string class_id = 1;
-  string id       = 2;
-  string owner    = 3;
+
+  // id is a unique identifier of the nft
+  string id = 2;
+
+  // owner is the owner address of the nft
+  string owner = 3;
 }
 
 // EventBurn is emitted on Burn
 message EventBurn {
+  // class_id associated with the nft
   string class_id = 1;
-  string id       = 2;
-  string owner    = 3;
+
+  // id is a unique identifier of the nft
+  string id = 2;
+
+  // owner is the owner address of the nft
+  string owner = 3;
 }
diff --git a/proto/cosmos/nft/v1beta1/genesis.proto b/proto/cosmos/nft/v1beta1/genesis.proto
index 6f36ed34d..75b5245a9 100644
--- a/proto/cosmos/nft/v1beta1/genesis.proto
+++ b/proto/cosmos/nft/v1beta1/genesis.proto
@@ -9,7 +9,9 @@ option go_package = "github.com/cosmos/cosmos-sdk/x/nft";
 message GenesisState {
   // class defines the class of the nft type.
   repeated cosmos.nft.v1beta1.Class classes = 1;
-  repeated Entry                    entries = 2;
+
+  // entry defines all nft owned by a person.
+  repeated Entry entries = 2;
 }
 
 // Entry Defines all nft owned by a person
diff --git a/proto/cosmos/nft/v1beta1/query.proto b/proto/cosmos/nft/v1beta1/query.proto
index c1d8070f4..ae482e4ce 100644
--- a/proto/cosmos/nft/v1beta1/query.proto
+++ b/proto/cosmos/nft/v1beta1/query.proto
@@ -48,67 +48,91 @@ service Query {
 
 // QueryBalanceRequest is the request type for the Query/Balance RPC method
 message QueryBalanceRequest {
+  // class_id associated with the nft
   string class_id = 1;
-  string owner    = 2;
+
+  // owner is the owner address of the nft
+  string owner = 2;
 }
 
 // QueryBalanceResponse is the response type for the Query/Balance RPC method
 message QueryBalanceResponse {
+  // amount is the number of all NFTs of a given class owned by the owner
   uint64 amount = 1;
 }
 
 // QueryOwnerRequest is the request type for the Query/Owner RPC method
 message QueryOwnerRequest {
+  // class_id associated with the nft
   string class_id = 1;
-  string id       = 2;
+
+  // id is a unique identifier of the NFT
+  string id = 2;
 }
 
 // QueryOwnerResponse is the response type for the Query/Owner RPC method
 message QueryOwnerResponse {
+  // owner is the owner address of the nft
   string owner = 1;
 }
 
 // QuerySupplyRequest is the request type for the Query/Supply RPC method
 message QuerySupplyRequest {
+  // class_id associated with the nft
   string class_id = 1;
 }
 
 // QuerySupplyResponse is the response type for the Query/Supply RPC method
 message QuerySupplyResponse {
+  // amount is the number of all NFTs from the given class
   uint64 amount = 1;
 }
 
 // QueryNFTstRequest is the request type for the Query/NFTs RPC method
 message QueryNFTsRequest {
-  string                                class_id   = 1;
-  string                                owner      = 2;
+  // class_id associated with the nft
+  string class_id = 1;
+
+  // owner is the owner address of the nft
+  string owner = 2;
+
+  // pagination defines an optional pagination for the request.
   cosmos.base.query.v1beta1.PageRequest pagination = 3;
 }
 
 // QueryNFTsResponse is the response type for the Query/NFTs RPC methods
 message QueryNFTsResponse {
-  repeated cosmos.nft.v1beta1.NFT        nfts       = 1;
+  // NFT defines the NFT
+  repeated cosmos.nft.v1beta1.NFT nfts = 1;
+
+  // pagination defines the pagination in the response.
   cosmos.base.query.v1beta1.PageResponse pagination = 2;
 }
 
 // QueryNFTRequest is the request type for the Query/NFT RPC method
 message QueryNFTRequest {
+  // class_id associated with the nft
   string class_id = 1;
-  string id       = 2;
+
+  // id is a unique identifier of the NFT
+  string id = 2;
 }
 
 // QueryNFTResponse is the response type for the Query/NFT RPC method
 message QueryNFTResponse {
+  // owner is the owner address of the nft
   cosmos.nft.v1beta1.NFT nft = 1;
 }
 
 // QueryClassRequest is the request type for the Query/Class RPC method
 message QueryClassRequest {
+  // class_id associated with the nft
   string class_id = 1;
 }
 
 // QueryClassResponse is the response type for the Query/Class RPC method
 message QueryClassResponse {
+  // class defines the class of the nft type.
   cosmos.nft.v1beta1.Class class = 1;
 }
 
@@ -120,6 +144,9 @@ message QueryClassesRequest {
 
 // QueryClassesResponse is the response type for the Query/Classes RPC method
 message QueryClassesResponse {
-  repeated cosmos.nft.v1beta1.Class      classes    = 1;
+  // class defines the class of the nft type.
+  repeated cosmos.nft.v1beta1.Class classes = 1;
+
+  // pagination defines the pagination in the response.
   cosmos.base.query.v1beta1.PageResponse pagination = 2;
 }
diff --git a/x/nft/client/cli/query_test.go b/x/nft/client/cli/query_test.go
index a8bd55ed1..540d4d8c9 100644
--- a/x/nft/client/cli/query_test.go
+++ b/x/nft/client/cli/query_test.go
@@ -1,9 +1,13 @@
 package cli_test
 
 import (
+	"context"
 	"fmt"
+	"io"
 
+	"github.com/cosmos/cosmos-sdk/client"
 	"github.com/cosmos/cosmos-sdk/client/flags"
+	svrcmd "github.com/cosmos/cosmos-sdk/server/cmd"
 	"github.com/cosmos/cosmos-sdk/testutil"
 	clitestutil "github.com/cosmos/cosmos-sdk/testutil/cli"
 	"github.com/cosmos/cosmos-sdk/x/nft"
@@ -12,111 +16,119 @@ import (
 
 func (s *CLITestSuite) TestQueryClass() {
 	testCases := []struct {
-		name string
-		args struct {
-			ClassID string
-		}
-		expectErr bool
+		name         string
+		args         []string
+		expCmdOutput string
 	}{
 		{
-			name: "valid case",
-			args: struct {
-				ClassID string
-			}{
-				ClassID: testClassID,
-			},
-			expectErr: false,
+			name:         "json output",
+			args:         []string{testClassID, fmt.Sprintf("--%s=json", flags.FlagOutput)},
+			expCmdOutput: `[kitty --output=json]`,
+		},
+		{
+			name:         "text output",
+			args:         []string{testClassID, fmt.Sprintf("--%s=text", flags.FlagOutput)},
+			expCmdOutput: `[kitty --output=text]`,
 		},
 	}
 
 	for _, tc := range testCases {
 		s.Run(tc.name, func() {
 			cmd := cli.GetCmdQueryClass()
-			var args []string
-			args = append(args, tc.args.ClassID)
-			args = append(args, fmt.Sprintf("--%s=json", flags.FlagOutput))
-			out, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, args)
 
-			if tc.expectErr {
-				s.Require().Error(err)
-			} else {
-				s.Require().NoError(err)
-				var result nft.QueryClassResponse
-				err = s.clientCtx.Codec.UnmarshalJSON(out.Bytes(), &result)
-				s.Require().NoError(err)
-			}
+			ctx := svrcmd.CreateExecuteContext(context.Background())
+
+			cmd.SetOut(io.Discard)
+			s.Require().NotNil(cmd)
+
+			cmd.SetContext(ctx)
+			cmd.SetArgs(tc.args)
+			s.Require().NoError(client.SetCmdClientContextHandler(s.baseCtx, cmd))
+
+			s.Require().Contains(fmt.Sprint(cmd), "class [class-id] [] [] query an NFT class based on its id")
+			s.Require().Contains(fmt.Sprint(cmd), tc.expCmdOutput)
+
+			_, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, tc.args)
+			s.Require().NoError(err)
 		})
 	}
 }
 
 func (s *CLITestSuite) TestQueryClasses() {
 	testCases := []struct {
-		name      string
-		expectErr bool
+		name         string
+		flagArgs     []string
+		expCmdOutput string
 	}{
 		{
-			name:      "no params",
-			expectErr: false,
+			name:         "json output",
+			flagArgs:     []string{fmt.Sprintf("--%s=json", flags.FlagOutput)},
+			expCmdOutput: `[--output=json]`,
+		},
+		{
+			name:         "text output",
+			flagArgs:     []string{fmt.Sprintf("--%s=text", flags.FlagOutput)},
+			expCmdOutput: `[--output=text]`,
 		},
 	}
 
 	for _, tc := range testCases {
 		s.Run(tc.name, func() {
 			cmd := cli.GetCmdQueryClasses()
-			var args []string
-			args = append(args, fmt.Sprintf("--%s=json", flags.FlagOutput))
-			out, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, args)
-			if tc.expectErr {
-				s.Require().Error(err)
-			} else {
-				s.Require().NoError(err)
-				var result nft.QueryClassesResponse
-				err = s.clientCtx.Codec.UnmarshalJSON(out.Bytes(), &result)
-				s.Require().NoError(err)
-			}
+			ctx := svrcmd.CreateExecuteContext(context.Background())
+
+			cmd.SetOut(io.Discard)
+			s.Require().NotNil(cmd)
+
+			cmd.SetContext(ctx)
+			cmd.SetArgs(tc.flagArgs)
+			s.Require().NoError(client.SetCmdClientContextHandler(s.baseCtx, cmd))
+
+			s.Require().Contains(fmt.Sprint(cmd), "classes [] [] query all NFT classes")
+			s.Require().Contains(fmt.Sprint(cmd), tc.expCmdOutput)
+
+			_, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, tc.flagArgs)
+			s.Require().NoError(err)
 		})
 	}
 }
 
 func (s *CLITestSuite) TestQueryNFT() {
 	testCases := []struct {
-		name string
-		args struct {
-			ClassID string
-			ID      string
-		}
-		expectErr bool
+		name         string
+		args         []string
+		expCmdOutput string
 	}{
 		{
-			name: "valid case",
-			args: struct {
-				ClassID string
-				ID      string
-			}{
-				ClassID: testClassID,
-				ID:      testID,
-			},
-			expectErr: false,
+			name:         "json output",
+			args:         []string{testClassID, testID, fmt.Sprintf("--%s=json", flags.FlagOutput)},
+			expCmdOutput: `[kitty kitty1 --output=json]`,
+		},
+		{
+			name:         "text output",
+			args:         []string{testClassID, testID, fmt.Sprintf("--%s=text", flags.FlagOutput)},
+			expCmdOutput: `[kitty kitty1 --output=text]`,
 		},
 	}
 
 	for _, tc := range testCases {
 		s.Run(tc.name, func() {
 			cmd := cli.GetCmdQueryNFT()
-			var args []string
-			args = append(args, tc.args.ClassID)
-			args = append(args, tc.args.ID)
-			args = append(args, fmt.Sprintf("--%s=json", flags.FlagOutput))
 
-			out, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, args)
-			if tc.expectErr {
-				s.Require().Error(err)
-			} else {
-				s.Require().NoError(err)
-				var result nft.QueryNFTResponse
-				err = s.clientCtx.Codec.UnmarshalJSON(out.Bytes(), &result)
-				s.Require().NoError(err)
-			}
+			ctx := svrcmd.CreateExecuteContext(context.Background())
+
+			cmd.SetOut(io.Discard)
+			s.Require().NotNil(cmd)
+
+			cmd.SetContext(ctx)
+			cmd.SetArgs(tc.args)
+			s.Require().NoError(client.SetCmdClientContextHandler(s.baseCtx, cmd))
+
+			s.Require().Contains(fmt.Sprint(cmd), "nft [class-id] [nft-id] [] [] query an NFT based on its class and id")
+			s.Require().Contains(fmt.Sprint(cmd), tc.expCmdOutput)
+
+			_, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, tc.args)
+			s.Require().NoError(err)
 		})
 	}
 }
@@ -131,6 +143,7 @@ func (s *CLITestSuite) TestQueryNFTs() {
 			Owner   string
 		}
 		expectErr bool
+		expErrMsg string
 	}{
 		{
 			name: "empty class id and owner",
@@ -139,6 +152,7 @@ func (s *CLITestSuite) TestQueryNFTs() {
 				Owner   string
 			}{},
 			expectErr: true,
+			expErrMsg: "must provide at least one of classID or owner",
 		},
 		{
 			name: "valid case",
@@ -164,6 +178,7 @@ func (s *CLITestSuite) TestQueryNFTs() {
 			out, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, args)
 			if tc.expectErr {
 				s.Require().Error(err)
+				s.Require().Contains(err.Error(), tc.expErrMsg)
 			} else {
 				s.Require().NoError(err)
 				var result nft.QueryNFTsResponse
@@ -176,43 +191,40 @@ func (s *CLITestSuite) TestQueryNFTs() {
 
 func (s *CLITestSuite) TestQueryOwner() {
 	testCases := []struct {
-		name string
-		args struct {
-			ClassID string
-			ID      string
-		}
-		expectErr bool
+		name         string
+		args         []string
+		expCmdOutput string
 	}{
 		{
-			name: "valid case",
-			args: struct {
-				ClassID string
-				ID      string
-			}{
-				ClassID: testClassID,
-				ID:      testID,
-			},
-			expectErr: false,
+			name:         "json output",
+			args:         []string{testClassID, testID, fmt.Sprintf("--%s=json", flags.FlagOutput)},
+			expCmdOutput: `[kitty kitty1 --output=json]`,
+		},
+		{
+			name:         "text output",
+			args:         []string{testClassID, testID, fmt.Sprintf("--%s=text", flags.FlagOutput)},
+			expCmdOutput: `[kitty kitty1 --output=text]`,
 		},
 	}
 
 	for _, tc := range testCases {
 		s.Run(tc.name, func() {
 			cmd := cli.GetCmdQueryOwner()
-			var args []string
-			args = append(args, tc.args.ClassID)
-			args = append(args, tc.args.ID)
-			args = append(args, fmt.Sprintf("--%s=json", flags.FlagOutput))
 
-			out, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, args)
-			if tc.expectErr {
-				s.Require().Error(err)
-			} else {
-				s.Require().NoError(err)
-				var result nft.QueryOwnerResponse
-				err = s.clientCtx.Codec.UnmarshalJSON(out.Bytes(), &result)
-				s.Require().NoError(err)
-			}
+			ctx := svrcmd.CreateExecuteContext(context.Background())
+
+			cmd.SetOut(io.Discard)
+			s.Require().NotNil(cmd)
+
+			cmd.SetContext(ctx)
+			cmd.SetArgs(tc.args)
+			s.Require().NoError(client.SetCmdClientContextHandler(s.baseCtx, cmd))
+
+			s.Require().Contains(fmt.Sprint(cmd), "owner [class-id] [nft-id] [] [] query the owner of the NFT based on its class and id")
+			s.Require().Contains(fmt.Sprint(cmd), tc.expCmdOutput)
+
+			_, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, tc.args)
+			s.Require().NoError(err)
 		})
 	}
 }
@@ -221,82 +233,75 @@ func (s *CLITestSuite) TestQueryBalance() {
 	accounts := testutil.CreateKeyringAccounts(s.T(), s.kr, 1)
 
 	testCases := []struct {
-		name string
-		args struct {
-			ClassID string
-			Owner   string
-		}
-		expectErr bool
+		name         string
+		args         []string
+		expCmdOutput string
 	}{
 		{
-			name: "valid case",
-			args: struct {
-				ClassID string
-				Owner   string
-			}{
-				ClassID: testClassID,
-				Owner:   accounts[0].Address.String(),
-			},
-			expectErr: false,
+			name:         "json output",
+			args:         []string{accounts[0].Address.String(), testClassID, fmt.Sprintf("--%s=json", flags.FlagOutput)},
+			expCmdOutput: fmt.Sprintf("%s kitty --output=json", accounts[0].Address.String()),
+		},
+		{
+			name:         "text output",
+			args:         []string{accounts[0].Address.String(), testClassID, fmt.Sprintf("--%s=text", flags.FlagOutput)},
+			expCmdOutput: fmt.Sprintf("%s kitty --output=text", accounts[0].Address.String()),
 		},
 	}
 
 	for _, tc := range testCases {
 		s.Run(tc.name, func() {
 			cmd := cli.GetCmdQueryBalance()
-			var args []string
-			args = append(args, tc.args.Owner)
-			args = append(args, tc.args.ClassID)
-			args = append(args, fmt.Sprintf("--%s=json", flags.FlagOutput))
 
-			out, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, args)
-			if tc.expectErr {
-				s.Require().Error(err)
-			} else {
-				s.Require().NoError(err)
-				var result nft.QueryBalanceResponse
-				err = s.clientCtx.Codec.UnmarshalJSON(out.Bytes(), &result)
-				s.Require().NoError(err)
-			}
+			ctx := svrcmd.CreateExecuteContext(context.Background())
+
+			cmd.SetOut(io.Discard)
+			s.Require().NotNil(cmd)
+
+			cmd.SetContext(ctx)
+			cmd.SetArgs(tc.args)
+			s.Require().NoError(client.SetCmdClientContextHandler(s.baseCtx, cmd))
+
+			s.Require().Contains(fmt.Sprint(cmd), "balance [owner] [class-id] [] [] query the number of NFTs of a given class owned by the owner")
+			s.Require().Contains(fmt.Sprint(cmd), tc.expCmdOutput)
+
+			_, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, tc.args)
+			s.Require().NoError(err)
 		})
 	}
 }
 
 func (s *CLITestSuite) TestQuerySupply() {
 	testCases := []struct {
-		name string
-		args struct {
-			ClassID string
-		}
-		expectErr bool
+		name         string
+		args         []string
+		expCmdOutput string
 	}{
 		{
-			name: "valid case",
-			args: struct {
-				ClassID string
-			}{
-				ClassID: testClassID,
-			},
-			expectErr: false,
+			name:         "valid case",
+			args:         []string{testClassID, fmt.Sprintf("--%s=json", flags.FlagOutput)},
+			expCmdOutput: `[kitty --output=json]`,
 		},
 	}
 
 	for _, tc := range testCases {
 		s.Run(tc.name, func() {
 			cmd := cli.GetCmdQuerySupply()
-			var args []string
-			args = append(args, tc.args.ClassID)
-			args = append(args, fmt.Sprintf("--%s=json", flags.FlagOutput))
 
-			out, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, args)
-			if tc.expectErr {
-				s.Require().Error(err)
-			} else {
-				s.Require().NoError(err)
-				var result nft.QuerySupplyResponse
-				err = s.clientCtx.Codec.UnmarshalJSON(out.Bytes(), &result)
-				s.Require().NoError(err)
-			}
+			ctx := svrcmd.CreateExecuteContext(context.Background())
+
+			cmd.SetOut(io.Discard)
+			s.Require().NotNil(cmd)
+
+			cmd.SetContext(ctx)
+			cmd.SetArgs(tc.args)
+			s.Require().NoError(client.SetCmdClientContextHandler(s.baseCtx, cmd))
+
+			s.Require().Contains(fmt.Sprint(cmd), "supply [class-id] [] [] query the number of nft based on the class")
+			s.Require().Contains(fmt.Sprint(cmd), tc.expCmdOutput)
+
+			_, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, tc.args)
+			s.Require().NoError(err)
 		})
 	}
 }
diff --git a/x/nft/client/cli/tx.go b/x/nft/client/cli/tx.go
index 45320a97a..4f9c735b8 100644
--- a/x/nft/client/cli/tx.go
+++ b/x/nft/client/cli/tx.go
@@ -31,6 +31,7 @@ func GetTxCmd() *cobra.Command {
 	return nftTxCmd
 }
 
+// NewCmdSend creates a CLI command for MsgSend.
 func NewCmdSend() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "send [class-id] [nft-id] [receiver] --from [sender]",
diff --git a/x/nft/client/cli/tx_test.go b/x/nft/client/cli/tx_test.go
index 7ef912782..dfa63233c 100644
--- a/x/nft/client/cli/tx_test.go
+++ b/x/nft/client/cli/tx_test.go
@@ -126,7 +126,7 @@ func (s *CLITestSuite) SetupSuite() {
 func (s *CLITestSuite) TestCLITxSend() {
 	accounts := testutil.CreateKeyringAccounts(s.T(), s.kr, 1)
 
-	args := []string{
+	extraArgs := []string{
 		fmt.Sprintf("--%s=%s", flags.FlagFrom, OwnerName),
 		fmt.Sprintf("--%s=true", flags.FlagSkipConfirmation),
 		fmt.Sprintf("--%s=%s", flags.FlagBroadcastMode, flags.BroadcastSync),
@@ -138,7 +138,41 @@ func (s *CLITestSuite) TestCLITxSend() {
 		args         []string
 		expectedCode uint32
 		expectErr    bool
+		expErrMsg    string
 	}{
+		{
+			"class id is empty",
+			[]string{
+				"",
+				testID,
+				accounts[0].Address.String(),
+			},
+			0,
+			true,
+			"empty class id",
+		},
+		{
+			"nft id is empty",
+			[]string{
+				testClassID,
+				"",
+				accounts[0].Address.String(),
+			},
+			0,
+			true,
+			"empty nft id",
+		},
+		{
+			"invalid receiver address",
+			[]string{
+				testClassID,
+				testID,
+				"invalid receiver",
+			},
+			0,
+			true,
+			"Invalid receiver address",
+		},
 		{
 			"valid transaction",
 			[]string{
@@ -148,13 +182,14 @@ func (s *CLITestSuite) TestCLITxSend() {
 			},
 			0,
 			false,
+			"",
 		},
 	}
 
 	for _, tc := range testCases {
 		tc := tc
 		s.Run(tc.name, func() {
-			args = append(args, tc.args...)
+			args := append(tc.args, extraArgs...)
 			cmd := cli.NewCmdSend()
 			cmd.SetContext(s.ctx)
 			cmd.SetArgs(args)
@@ -164,6 +199,7 @@ func (s *CLITestSuite) TestCLITxSend() {
 			out, err := clitestutil.ExecTestCLICmd(s.clientCtx, cmd, args)
 			if tc.expectErr {
 				s.Require().Error(err)
+				s.Require().Contains(err.Error(), tc.expErrMsg)
 			} else {
 				var txResp sdk.TxResponse
 				s.Require().NoError(err)
diff --git a/x/nft/codec.go b/x/nft/codec.go
index d98e836c3..12a4250cb 100644
--- a/x/nft/codec.go
+++ b/x/nft/codec.go
@@ -6,6 +6,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/types/msgservice"
 )
 
+// RegisterInterfaces registers the interfaces types with the interface registry.
 func RegisterInterfaces(registry types.InterfaceRegistry) {
 	registry.RegisterImplementations((*sdk.Msg)(nil),
 		&MsgSend{},
diff --git a/x/nft/errors.go b/x/nft/errors.go
index 771146f39..ff8fd1cc1 100644
--- a/x/nft/errors.go
+++ b/x/nft/errors.go
@@ -6,9 +6,9 @@ import (
 
 // x/nft module sentinel errors
 var (
-	ErrClassExists    = errors.Register(ModuleName, 3, "nft class already exist")
+	ErrClassExists    = errors.Register(ModuleName, 3, "nft class already exists")
 	ErrClassNotExists = errors.Register(ModuleName, 4, "nft class does not exist")
-	ErrNFTExists      = errors.Register(ModuleName, 5, "nft already exist")
+	ErrNFTExists      = errors.Register(ModuleName, 5, "nft already exists")
 	ErrNFTNotExists   = errors.Register(ModuleName, 6, "nft does not exist")
 	ErrEmptyClassID   = errors.Register(ModuleName, 7, "empty class id")
 	ErrEmptyNFTID     = errors.Register(ModuleName, 8, "empty nft id")
diff --git a/x/nft/event.pb.go b/x/nft/event.pb.go
index d5540b618..56950509f 100644
--- a/x/nft/event.pb.go
+++ b/x/nft/event.pb.go
@@ -24,9 +24,13 @@ const _ = proto.GoGoProtoPackageIsVersion3 // please upgrade the proto package
 
 // EventSend is emitted on Msg/Send
 type EventSend struct {
-	ClassId  string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Id       string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
-	Sender   string `protobuf:"bytes,3,opt,name=sender,proto3" json:"sender,omitempty"`
+	// class_id associated with the nft
+	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
+	// id is a unique identifier of the nft
+	Id string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
+	// sender is the address of the owner of nft
+	Sender string `protobuf:"bytes,3,opt,name=sender,proto3" json:"sender,omitempty"`
+	// receiver is the receiver address of nft
 	Receiver string `protobuf:"bytes,4,opt,name=receiver,proto3" json:"receiver,omitempty"`
 }
 
@@ -93,9 +97,12 @@ func (m *EventSend) GetReceiver() string {
 
 // EventMint is emitted on Mint
 type EventMint struct {
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Id      string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
-	Owner   string `protobuf:"bytes,3,opt,name=owner,proto3" json:"owner,omitempty"`
+	// id is a unique identifier of the nft
+	Id string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
+	// owner is the owner address of the nft
+	Owner string `protobuf:"bytes,3,opt,name=owner,proto3" json:"owner,omitempty"`
 }
 
 func (m *EventMint) Reset()         { *m = EventMint{} }
@@ -154,9 +161,12 @@ func (m *EventMint) GetOwner() string {
 
 // EventBurn is emitted on Burn
 type EventBurn struct {
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Id      string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
-	Owner   string `protobuf:"bytes,3,opt,name=owner,proto3" json:"owner,omitempty"`
+	// id is a unique identifier of the nft
+	Id string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
+	// owner is the owner address of the nft
+	Owner string `protobuf:"bytes,3,opt,name=owner,proto3" json:"owner,omitempty"`
 }
 
 func (m *EventBurn) Reset()         { *m = EventBurn{} }
diff --git a/x/nft/genesis.go b/x/nft/genesis.go
index 75124ea35..30b743a68 100644
--- a/x/nft/genesis.go
+++ b/x/nft/genesis.go
@@ -4,7 +4,7 @@ import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
-// ValidateGenesis check the given genesis state has no integrity issues
+// ValidateGenesis checks that the given genesis state has no integrity issues
 func ValidateGenesis(data GenesisState) error {
 	for _, class := range data.Classes {
 		if len(class.Id) == 0 {
@@ -24,7 +24,7 @@ func ValidateGenesis(data GenesisState) error {
 	return nil
 }
 
-// DefaultGenesisState - Return a default genesis state
+// DefaultGenesisState - Returns a default genesis state
 func DefaultGenesisState() *GenesisState {
 	return &GenesisState{}
 }
diff --git a/x/nft/genesis.pb.go b/x/nft/genesis.pb.go
index 6ad3f3fc5..785ce0e5e 100644
--- a/x/nft/genesis.pb.go
+++ b/x/nft/genesis.pb.go
@@ -26,6 +26,7 @@ const _ = proto.GoGoProtoPackageIsVersion3 // please upgrade the proto package
 type GenesisState struct {
 	// class defines the class of the nft type.
 	Classes []*Class `protobuf:"bytes,1,rep,name=classes,proto3" json:"classes,omitempty"`
+	// entry defines all nft owned by a person.
 	Entries []*Entry `protobuf:"bytes,2,rep,name=entries,proto3" json:"entries,omitempty"`
 }
 
diff --git a/x/nft/keeper/class.go b/x/nft/keeper/class.go
index d887ec662..00bbd90e1 100644
--- a/x/nft/keeper/class.go
+++ b/x/nft/keeper/class.go
@@ -20,7 +20,7 @@ func (k Keeper) SaveClass(ctx sdk.Context, class nft.Class) error {
 	return nil
 }
 
-// UpdateClass defines a method for updating a exist nft class
+// UpdateClass defines a method for updating an exist nft class
 func (k Keeper) UpdateClass(ctx sdk.Context, class nft.Class) error {
 	if !k.HasClass(ctx, class.Id) {
 		return sdkerrors.Wrap(nft.ErrClassNotExists, class.Id)
diff --git a/x/nft/keeper/genesis.go b/x/nft/keeper/genesis.go
index 116bf0bd2..ff5886e28 100644
--- a/x/nft/keeper/genesis.go
+++ b/x/nft/keeper/genesis.go
@@ -7,7 +7,8 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/nft"
 )
 
-// InitGenesis new nft genesis
+// InitGenesis initializes the nft module's genesis state from a given
+// genesis state.
 func (k Keeper) InitGenesis(ctx sdk.Context, data *nft.GenesisState) {
 	for _, class := range data.Classes {
 		if err := k.SaveClass(ctx, *class); err != nil {
diff --git a/x/nft/keeper/grpc_query.go b/x/nft/keeper/grpc_query.go
index e409a78c0..0c4026e20 100644
--- a/x/nft/keeper/grpc_query.go
+++ b/x/nft/keeper/grpc_query.go
@@ -14,10 +14,6 @@ var _ nft.QueryServer = Keeper{}
 
 // Balance return the number of NFTs of a given class owned by the owner, same as balanceOf in ERC721
 func (k Keeper) Balance(goCtx context.Context, r *nft.QueryBalanceRequest) (*nft.QueryBalanceResponse, error) {
-	if r == nil {
-		return nil, sdkerrors.ErrInvalidRequest.Wrap("empty request")
-	}
-
 	if len(r.ClassId) == 0 {
 		return nil, nft.ErrEmptyClassID
 	}
@@ -34,10 +30,6 @@ func (k Keeper) Balance(goCtx context.Context, r *nft.QueryBalanceRequest) (*nft
 
 // Owner return the owner of the NFT based on its class and id, same as ownerOf in ERC721
 func (k Keeper) Owner(goCtx context.Context, r *nft.QueryOwnerRequest) (*nft.QueryOwnerResponse, error) {
-	if r == nil {
-		return nil, sdkerrors.ErrInvalidRequest.Wrap("empty request")
-	}
-
 	if len(r.ClassId) == 0 {
 		return nil, nft.ErrEmptyClassID
 	}
@@ -53,10 +45,6 @@ func (k Keeper) Owner(goCtx context.Context, r *nft.QueryOwnerRequest) (*nft.Que
 
 // Supply return the number of NFTs from the given class, same as totalSupply of ERC721.
 func (k Keeper) Supply(goCtx context.Context, r *nft.QuerySupplyRequest) (*nft.QuerySupplyResponse, error) {
-	if r == nil {
-		return nil, sdkerrors.ErrInvalidRequest.Wrap("empty request")
-	}
-
 	if len(r.ClassId) == 0 {
 		return nil, nft.ErrEmptyClassID
 	}
@@ -67,10 +55,6 @@ func (k Keeper) Supply(goCtx context.Context, r *nft.QuerySupplyRequest) (*nft.Q
 
 // NFTs queries all NFTs of a given class or owner (at least one must be provided), similar to tokenByIndex in ERC721Enumerable
 func (k Keeper) NFTs(goCtx context.Context, r *nft.QueryNFTsRequest) (*nft.QueryNFTsResponse, error) {
-	if r == nil {
-		return nil, sdkerrors.ErrInvalidRequest.Wrap("empty request")
-	}
-
 	var err error
 	var owner sdk.AccAddress
 
@@ -129,10 +113,6 @@ func (k Keeper) NFTs(goCtx context.Context, r *nft.QueryNFTsRequest) (*nft.Query
 
 // NFT return an NFT based on its class and id.
 func (k Keeper) NFT(goCtx context.Context, r *nft.QueryNFTRequest) (*nft.QueryNFTResponse, error) {
-	if r == nil {
-		return nil, sdkerrors.ErrInvalidRequest.Wrap("empty request")
-	}
-
 	if len(r.ClassId) == 0 {
 		return nil, nft.ErrEmptyClassID
 	}
@@ -150,10 +130,6 @@ func (k Keeper) NFT(goCtx context.Context, r *nft.QueryNFTRequest) (*nft.QueryNF
 
 // Class return an NFT class based on its id
 func (k Keeper) Class(goCtx context.Context, r *nft.QueryClassRequest) (*nft.QueryClassResponse, error) {
-	if r == nil {
-		return nil, sdkerrors.ErrInvalidRequest.Wrap("empty request")
-	}
-
 	if len(r.ClassId) == 0 {
 		return nil, nft.ErrEmptyClassID
 	}
@@ -168,10 +144,6 @@ func (k Keeper) Class(goCtx context.Context, r *nft.QueryClassRequest) (*nft.Que
 
 // Classes return all NFT classes
 func (k Keeper) Classes(goCtx context.Context, r *nft.QueryClassesRequest) (*nft.QueryClassesResponse, error) {
-	if r == nil {
-		return nil, sdkerrors.ErrInvalidRequest.Wrap("empty request")
-	}
-
 	ctx := sdk.UnwrapSDKContext(goCtx)
 	store := ctx.KVStore(k.storeKey)
 	classStore := prefix.NewStore(store, ClassKey)
diff --git a/x/nft/keeper/msg_server.go b/x/nft/keeper/msg_server.go
index fc14a6055..3fa78a957 100644
--- a/x/nft/keeper/msg_server.go
+++ b/x/nft/keeper/msg_server.go
@@ -10,7 +10,7 @@ import (
 
 var _ nft.MsgServer = Keeper{}
 
-// Send implement Send method of the types.MsgServer.
+// Send implements Send method of the types.MsgServer.
 func (k Keeper) Send(goCtx context.Context, msg *nft.MsgSend) (*nft.MsgSendResponse, error) {
 	ctx := sdk.UnwrapSDKContext(goCtx)
 	sender, err := sdk.AccAddressFromBech32(msg.Sender)
diff --git a/x/nft/keeper/msg_server_test.go b/x/nft/keeper/msg_server_test.go
new file mode 100644
index 000000000..f9f173575
--- /dev/null
+++ b/x/nft/keeper/msg_server_test.go
@@ -0,0 +1,110 @@
+package keeper_test
+
+import (
+	"fmt"
+
+	"github.com/cosmos/cosmos-sdk/x/nft"
+)
+
+var (
+	ExpClass = nft.Class{
+		Id:          testClassID,
+		Name:        testClassName,
+		Symbol:      testClassSymbol,
+		Description: testClassDescription,
+		Uri:         testClassURI,
+		UriHash:     testClassURIHash,
+	}
+
+	ExpNFT = nft.NFT{
+		ClassId: testClassID,
+		Id:      testID,
+		Uri:     testURI,
+	}
+)
+
+func (s *TestSuite) TestSend() {
+	err := s.nftKeeper.SaveClass(s.ctx, ExpClass)
+	s.Require().NoError(err)
+
+	actual, has := s.nftKeeper.GetClass(s.ctx, testClassID)
+	s.Require().True(has)
+	s.Require().EqualValues(ExpClass, actual)
+
+	err = s.nftKeeper.Mint(s.ctx, ExpNFT, s.addrs[0])
+	s.Require().NoError(err)
+
+	expGenesis := &nft.GenesisState{
+		Classes: []*nft.Class{&ExpClass},
+		Entries: []*nft.Entry{{
+			Owner: s.addrs[0].String(),
+			Nfts:  []*nft.NFT{&ExpNFT},
+		}},
+	}
+	genesis := s.nftKeeper.ExportGenesis(s.ctx)
+	s.Require().Equal(expGenesis, genesis)
+
+	testCases := []struct {
+		name   string
+		req    *nft.MsgSend
+		expErr bool
+		errMsg string
+	}{
+		{
+			name: "invalid class id",
+			req: &nft.MsgSend{
+				ClassId:  "invalid ClassId",
+				Id:       testID,
+				Sender:   s.addrs[0].String(),
+				Receiver: s.addrs[1].String(),
+			},
+			expErr: true,
+			errMsg: "unauthorized",
+		},
+		{
+			name: "invalid nft id",
+			req: &nft.MsgSend{
+				ClassId:  testClassID,
+				Id:       "invalid Id",
+				Sender:   s.addrs[0].String(),
+				Receiver: s.addrs[1].String(),
+			},
+			expErr: true,
+			errMsg: "unauthorized",
+		},
+		{
+			name: "unauthorized sender",
+			req: &nft.MsgSend{
+				ClassId:  testClassID,
+				Id:       testID,
+				Sender:   s.addrs[1].String(),
+				Receiver: s.addrs[2].String(),
+			},
+			expErr: true,
+			errMsg: fmt.Sprintf("%s is not the owner of nft %s", s.addrs[1].String(), testID),
+		},
+		{
+			name: "valid transaction",
+			req: &nft.MsgSend{
+				ClassId:  testClassID,
+				Id:       testID,
+				Sender:   s.addrs[0].String(),
+				Receiver: s.addrs[1].String(),
+			},
+			expErr: false,
+			errMsg: "",
+		},
+	}
+
+	for _, tc := range testCases {
+		s.Run(tc.name, func() {
+			_, err := s.nftKeeper.Send(s.ctx, tc.req)
+			if tc.expErr {
+				s.Require().Error(err)
+				s.Require().Contains(err.Error(), tc.errMsg)
+			} else {
+				s.Require().NoError(err)
+			}
+		})
+	}
+}
diff --git a/x/nft/keys.go b/x/nft/keys.go
index b3c11046e..fac6adb7a 100644
--- a/x/nft/keys.go
+++ b/x/nft/keys.go
@@ -1,7 +1,7 @@
 package nft
 
 const (
-	// ModuleName module name
+	// ModuleName defines the name of the nft module
 	ModuleName = "nft"
 
 	// StoreKey is the default store key for nft
diff --git a/x/nft/msgs.go b/x/nft/msgs.go
index 57926287b..0fdbd8749 100644
--- a/x/nft/msgs.go
+++ b/x/nft/msgs.go
@@ -2,6 +2,7 @@ package nft
 
 import (
 	"cosmossdk.io/errors"
+
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
 )
@@ -35,7 +36,7 @@ func (m MsgSend) ValidateBasic() error {
 	return nil
 }
 
-// GetSigners implements Msg
+// GetSigners returns the expected signers for MsgSend.
 func (m MsgSend) GetSigners() []sdk.AccAddress {
 	signer, _ := sdk.AccAddressFromBech32(m.Sender)
 	return []sdk.AccAddress{signer}
diff --git a/x/nft/query.pb.go b/x/nft/query.pb.go
index a5ab3e80d..cc628b80c 100644
--- a/x/nft/query.pb.go
+++ b/x/nft/query.pb.go
@@ -31,8 +31,10 @@ const _ = proto.GoGoProtoPackageIsVersion3 // please upgrade the proto package
 
 // QueryBalanceRequest is the request type for the Query/Balance RPC method
 type QueryBalanceRequest struct {
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Owner   string `protobuf:"bytes,2,opt,name=owner,proto3" json:"owner,omitempty"`
+	// owner is the owner address of the nft
+	Owner string `protobuf:"bytes,2,opt,name=owner,proto3" json:"owner,omitempty"`
 }
 
 func (m *QueryBalanceRequest) Reset()         { *m = QueryBalanceRequest{} }
@@ -84,6 +86,7 @@ func (m *QueryBalanceRequest) GetOwner() string {
 
 // QueryBalanceResponse is the response type for the Query/Balance RPC method
 type QueryBalanceResponse struct {
+	// amount is the number of all NFTs of a given class owned by the owner
 	Amount uint64 `protobuf:"varint,1,opt,name=amount,proto3" json:"amount,omitempty"`
 }
 
@@ -129,8 +132,10 @@ func (m *QueryBalanceResponse) GetAmount() uint64 {
 
 // QueryOwnerRequest is the request type for the Query/Owner RPC method
 type QueryOwnerRequest struct {
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Id      string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
+	// id is a unique identifier of the NFT
+	Id string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
 }
 
 func (m *QueryOwnerRequest) Reset()         { *m = QueryOwnerRequest{} }
@@ -182,6 +187,7 @@ func (m *QueryOwnerRequest) GetId() string {
 
 // QueryOwnerResponse is the response type for the Query/Owner RPC method
 type QueryOwnerResponse struct {
+	// owner is the owner address of the nft
 	Owner string `protobuf:"bytes,1,opt,name=owner,proto3" json:"owner,omitempty"`
 }
 
@@ -227,6 +233,7 @@ func (m *QueryOwnerResponse) GetOwner() string {
 
 // QuerySupplyRequest is the request type for the Query/Supply RPC method
 type QuerySupplyRequest struct {
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
 }
 
@@ -272,6 +279,7 @@ func (m *QuerySupplyRequest) GetClassId() string {
 
 // QuerySupplyResponse is the response type for the Query/Supply RPC method
 type QuerySupplyResponse struct {
+	// amount is the number of all NFTs from the given class
 	Amount uint64 `protobuf:"varint,1,opt,name=amount,proto3" json:"amount,omitempty"`
 }
 
@@ -317,8 +325,11 @@ func (m *QuerySupplyResponse) GetAmount() uint64 {
 
 // QueryNFTstRequest is the request type for the Query/NFTs RPC method
 type QueryNFTsRequest struct {
-	ClassId    string             `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Owner      string             `protobuf:"bytes,2,opt,name=owner,proto3" json:"owner,omitempty"`
+	// class_id associated with the nft
+	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
+	// owner is the owner address of the nft
+	Owner string `protobuf:"bytes,2,opt,name=owner,proto3" json:"owner,omitempty"`
+	// pagination defines an optional pagination for the request.
 	Pagination *query.PageRequest `protobuf:"bytes,3,opt,name=pagination,proto3" json:"pagination,omitempty"`
 }
 
@@ -378,7 +389,9 @@ func (m *QueryNFTsRequest) GetPagination() *query.PageRequest {
 
 // QueryNFTsResponse is the response type for the Query/NFTs RPC methods
 type QueryNFTsResponse struct {
-	Nfts       []*NFT              `protobuf:"bytes,1,rep,name=nfts,proto3" json:"nfts,omitempty"`
+	// NFT defines the NFT
+	Nfts []*NFT `protobuf:"bytes,1,rep,name=nfts,proto3" json:"nfts,omitempty"`
+	// pagination defines the pagination in the response.
 	Pagination *query.PageResponse `protobuf:"bytes,2,opt,name=pagination,proto3" json:"pagination,omitempty"`
 }
 
@@ -431,8 +444,10 @@ func (m *QueryNFTsResponse) GetPagination() *query.PageResponse {
 
 // QueryNFTRequest is the request type for the Query/NFT RPC method
 type QueryNFTRequest struct {
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
-	Id      string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
+	// id is a unique identifier of the NFT
+	Id string `protobuf:"bytes,2,opt,name=id,proto3" json:"id,omitempty"`
 }
 
 func (m *QueryNFTRequest) Reset()         { *m = QueryNFTRequest{} }
@@ -484,6 +499,7 @@ func (m *QueryNFTRequest) GetId() string {
 
 // QueryNFTResponse is the response type for the Query/NFT RPC method
 type QueryNFTResponse struct {
+	// owner is the owner address of the nft
 	Nft *NFT `protobuf:"bytes,1,opt,name=nft,proto3" json:"nft,omitempty"`
 }
 
@@ -529,6 +545,7 @@ func (m *QueryNFTResponse) GetNft() *NFT {
 
 // QueryClassRequest is the request type for the Query/Class RPC method
 type QueryClassRequest struct {
+	// class_id associated with the nft
 	ClassId string `protobuf:"bytes,1,opt,name=class_id,json=classId,proto3" json:"class_id,omitempty"`
 }
 
@@ -574,6 +591,7 @@ func (m *QueryClassRequest) GetClassId() string {
 
 // QueryClassResponse is the response type for the Query/Class RPC method
 type QueryClassResponse struct {
+	// class defines the class of the nft type.
 	Class *Class `protobuf:"bytes,1,opt,name=class,proto3" json:"class,omitempty"`
 }
 
@@ -665,7 +683,9 @@ func (m *QueryClassesRequest) GetPagination() *query.PageRequest {
 
 // QueryClassesResponse is the response type for the Query/Classes RPC method
 type QueryClassesResponse struct {
-	Classes    []*Class            `protobuf:"bytes,1,rep,name=classes,proto3" json:"classes,omitempty"`
+	// class defines the class of the nft type.
+	Classes []*Class `protobuf:"bytes,1,rep,name=classes,proto3" json:"classes,omitempty"`
+	// pagination defines the pagination in the response.
 	Pagination *query.PageResponse `protobuf:"bytes,2,opt,name=pagination,proto3" json:"pagination,omitempty"`
 }
 
diff --git a/x/nft/simulation/decoder.go b/x/nft/simulation/decoder.go
index 3af35a539..85eec43b7 100644
--- a/x/nft/simulation/decoder.go
+++ b/x/nft/simulation/decoder.go
@@ -11,7 +11,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/nft/keeper"
 )
 
-// NewDecodeStore returns a decoder function closure that umarshals the KVPair's
+// NewDecodeStore returns a decoder function closure that unmarshals the KVPair's
 // Value to the corresponding nft type.
 func NewDecodeStore(cdc codec.Codec) func(kvA, kvB kv.Pair) string {
 	return func(kvA, kvB kv.Pair) string {
diff --git a/x/nft/simulation/operations.go b/x/nft/simulation/operations.go
index b05f1c25f..60e079cc0 100644
--- a/x/nft/simulation/operations.go
+++ b/x/nft/simulation/operations.go
@@ -119,6 +119,7 @@ func SimulateMsgSend(
 	}
 }
 
+// randNFT picks a random NFT from a class belonging to the specified owner(minter).
 func randNFT(ctx sdk.Context, r *rand.Rand, k keeper.Keeper, minter sdk.AccAddress) (nft.NFT, error) {
 	c, err := randClass(ctx, r, k)
 	if err != nil {
@@ -141,6 +142,7 @@ func randNFT(ctx sdk.Context, r *rand.Rand, k keeper.Keeper, minter sdk.AccAddre
 	return n, nil
 }
 
+// randClass picks a random Class.
 func randClass(ctx sdk.Context, r *rand.Rand, k keeper.Keeper) (nft.Class, error) {
 	classes := k.GetClasses(ctx)
 	if len(classes) == 0 {