Add mcp-client-go

mcp-client-go/.env.example

@@ -0,0 +1 @@
+ANTHROPIC_API_KEY=your_api_key_here

mcp-client-go/README.md

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+# An LLM-Powered Chatbot MCP Client written in Go
+
+See the [Building MCP clients](https://modelcontextprotocol.io/tutorials/building-a-client) tutorial for more information.

mcp-client-go/go.mod

@@ -0,0 +1,18 @@
+module github.com/modelcontextprotocol/quickstart-resources/mcp-client-go
+
+go 1.25.1
+
+require (
+	github.com/anthropics/anthropic-sdk-go v1.14.0
+	github.com/joho/godotenv v1.5.1
+	github.com/modelcontextprotocol/go-sdk v1.0.0
+)
+
+require (
+	github.com/google/jsonschema-go v0.3.0 // indirect
+	github.com/tidwall/gjson v1.18.0 // indirect
+	github.com/tidwall/match v1.1.1 // indirect
+	github.com/tidwall/pretty v1.2.1 // indirect
+	github.com/tidwall/sjson v1.2.5 // indirect
+	github.com/yosida95/uritemplate/v3 v3.0.2 // indirect
+)

mcp-client-go/go.sum

@@ -0,0 +1,32 @@
+github.com/anthropics/anthropic-sdk-go v1.14.0 h1:EzNQvnZlaDHe2UPkoUySDz3ixRgNbwKdH8KtFpv7pi4=
+github.com/anthropics/anthropic-sdk-go v1.14.0/go.mod h1:WTz31rIUHUHqai2UslPpw5CwXrQP3geYBioRV4WOLvE=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
+github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
+github.com/google/jsonschema-go v0.3.0 h1:6AH2TxVNtk3IlvkkhjrtbUc4S8AvO0Xii0DxIygDg+Q=
+github.com/google/jsonschema-go v0.3.0/go.mod h1:r5quNTdLOYEz95Ru18zA0ydNbBuYoo9tgaYcxEYhJVE=
+github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
+github.com/modelcontextprotocol/go-sdk v1.0.0 h1:Z4MSjLi38bTgLrd/LjSmofqRqyBiVKRyQSJgw8q8V74=
+github.com/modelcontextprotocol/go-sdk v1.0.0/go.mod h1:nYtYQroQ2KQiM0/SbyEPUWQ6xs4B95gJjEalc9AQyOs=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+github.com/tidwall/gjson v1.14.2/go.mod h1:/wbyibRr2FHMks5tjHJ5F8dMZh3AcwJEMf5vlfC0lxk=
+github.com/tidwall/gjson v1.18.0 h1:FIDeeyB800efLX89e5a8Y0BNH+LOngJyGrIWxG2FKQY=
+github.com/tidwall/gjson v1.18.0/go.mod h1:/wbyibRr2FHMks5tjHJ5F8dMZh3AcwJEMf5vlfC0lxk=
+github.com/tidwall/match v1.1.1 h1:+Ho715JplO36QYgwN9PGYNhgZvoUSc9X2c80KVTi+GA=
+github.com/tidwall/match v1.1.1/go.mod h1:eRSPERbgtNPcGhD8UCthc6PmLEQXEWd3PRB5JTxsfmM=
+github.com/tidwall/pretty v1.2.0/go.mod h1:ITEVvHYasfjBbM0u2Pg8T2nJnzm8xPwvNhhsoaGGjNU=
+github.com/tidwall/pretty v1.2.1 h1:qjsOFOWWQl+N3RsoF5/ssm1pHmJJwhjlSbZ51I6wMl4=
+github.com/tidwall/pretty v1.2.1/go.mod h1:ITEVvHYasfjBbM0u2Pg8T2nJnzm8xPwvNhhsoaGGjNU=
+github.com/tidwall/sjson v1.2.5 h1:kLy8mja+1c9jlljvWTlSazM7cKDRfJuR/bOJhcY5NcY=
+github.com/tidwall/sjson v1.2.5/go.mod h1:Fvgq9kS/6ociJEDnK0Fk1cpYF4FIW6ZF7LAe+6jwd28=
+github.com/yosida95/uritemplate/v3 v3.0.2 h1:Ed3Oyj9yrmi9087+NczuL5BwkIc4wvTb5zIM+UJPGz4=
+github.com/yosida95/uritemplate/v3 v3.0.2/go.mod h1:ILOh0sOhIJR3+L/8afwt/kE++YT040gmv5BQTMR2HP4=
+golang.org/x/tools v0.34.0 h1:qIpSLOxeCYGg9TrcJokLBG4KFA6d795g0xkBkiESGlo=
+golang.org/x/tools v0.34.0/go.mod h1:pAP9OwEaY1CAW3HOmg3hLZC5Z0CCmzjAF2UQMSqNARg=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

mcp-client-go/main.go

@@ -0,0 +1,277 @@
+package main
+
+import (
+	"bufio"
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/anthropics/anthropic-sdk-go"
+	"github.com/anthropics/anthropic-sdk-go/option"
+	"github.com/joho/godotenv"
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+)
+
+var model anthropic.Model = anthropic.ModelClaudeSonnet4_5_20250929
+
+type MCPClient struct {
+	anthropic *anthropic.Client
+	session   *mcp.ClientSession
+	tools     []anthropic.ToolUnionParam
+}
+
+func NewMCPClient() (*MCPClient, error) {
+	// Load .env file
+	if err := godotenv.Load(); err != nil {
+		return nil, fmt.Errorf("failed to load .env file: %w", err)
+	}
+
+	apiKey := os.Getenv("ANTHROPIC_API_KEY")
+	if apiKey == "" {
+		return nil, fmt.Errorf("ANTHROPIC_API_KEY environment variable not set")
+	}
+
+	client := anthropic.NewClient(option.WithAPIKey(apiKey))
+
+	return &MCPClient{
+		anthropic: &client,
+	}, nil
+}
+
+func (c *MCPClient) ConnectToServer(ctx context.Context, serverArgs []string) error {
+	if len(serverArgs) == 0 {
+		return fmt.Errorf("no server command provided")
+	}
+
+	// Create command to spawn server process
+	cmd := exec.CommandContext(ctx, serverArgs[0], serverArgs[1:]...)
+
+	// Create MCP client
+	client := mcp.NewClient(
+		&mcp.Implementation{
+			Name:    "mcp-client-go",
+			Version: "0.1.0",
+		},
+		nil,
+	)
+
+	// Connect using CommandTransport
+	transport := &mcp.CommandTransport{
+		Command: cmd,
+	}
+
+	session, err := client.Connect(ctx, transport, nil)
+	if err != nil {
+		return fmt.Errorf("failed to connect to server: %w", err)
+	}
+
+	c.session = session
+
+	// List available tools
+	toolsResult, err := session.ListTools(ctx, &mcp.ListToolsParams{})
+	if err != nil {
+		return fmt.Errorf("failed to list tools: %w", err)
+	}
+
+	var toolNames []string
+
+	// Convert MCP tools to Anthropic tool format
+	for _, tool := range toolsResult.Tools {
+		toolNames = append(toolNames, tool.Name)
+		anthropicTool, err := mcpToolToAnthropicTool(tool)
+		if err != nil {
+			return fmt.Errorf("failed to convert mcp tool to anthropic tool: %w", err)
+		}
+		c.tools = append(c.tools, anthropicTool)
+	}
+
+	fmt.Printf("Connected to server with tools: %v\n", toolNames)
+	return nil
+}
+
+func mcpToolToAnthropicTool(tool *mcp.Tool) (anthropic.ToolUnionParam, error) {
+	var zeroTool anthropic.ToolUnionParam
+	schemaJSON, err := json.Marshal(tool.InputSchema)
+	if err != nil {
+		return zeroTool, fmt.Errorf("failed to marshal input schema of mcp tool: %w", err)
+	}
+	var schema anthropic.ToolInputSchemaParam
+	err = json.Unmarshal(schemaJSON, &schema)
+	if err != nil {
+		return zeroTool, fmt.Errorf("failed to unmarshal to anthropic input schema: %w", err)
+	}
+
+	toolParam := anthropic.ToolParam{
+		Name:        tool.Name,
+		Description: anthropic.String(tool.Description),
+		InputSchema: schema,
+	}
+
+	return anthropic.ToolUnionParam{
+		OfTool: &toolParam,
+	}, nil
+}
+
+func (c *MCPClient) ProcessQuery(ctx context.Context, query string) (string, error) {
+	if c.session == nil {
+		return "", fmt.Errorf("client is not connected to any server")
+	}
+
+	messages := []anthropic.MessageParam{
+		anthropic.NewUserMessage(anthropic.NewTextBlock(query)),
+	}
+
+	// Initial Claude API call with tools
+	response, err := c.anthropic.Messages.New(ctx, anthropic.MessageNewParams{
+		Model:     model,
+		MaxTokens: 1024,
+		Messages:  messages,
+		Tools:     c.tools,
+	})
+	if err != nil {
+		return "", fmt.Errorf("anthropic API request failed: %w", err)
+	}
+
+	var toolUseBlocks []anthropic.ToolUseBlock
+	var finalText []string
+	for _, block := range response.Content {
+		switch b := block.AsAny().(type) {
+		case anthropic.TextBlock:
+			finalText = append(finalText, b.Text)
+		case anthropic.ToolUseBlock:
+			toolUseBlocks = append(toolUseBlocks, b)
+		}
+	}
+
+	if len(toolUseBlocks) == 0 {
+		return strings.Join(finalText, "\n"), nil
+	}
+
+	// Append assistant's response to message history
+	messages = append(messages, response.ToParam())
+
+	// Execute each tool call and collect responses
+	var anthropicToolResults []anthropic.ContentBlockParamUnion
+	for _, toolUseBlock := range toolUseBlocks {
+		// Add information about the tool call to final text
+		finalText = append(finalText, fmt.Sprintf("[Calling tool %s with args %s]", toolUseBlock.Name, string(toolUseBlock.Input)))
+
+		// Call the MCP server tool
+		mcpToolResult, err := c.session.CallTool(ctx, &mcp.CallToolParams{
+			Name:      toolUseBlock.Name,
+			Arguments: toolUseBlock.Input,
+		})
+		if err != nil {
+			return "", fmt.Errorf("tool call %s failed: %w", toolUseBlock.Name, err)
+		}
+
+		// Serialize tool result
+		resultJSON, err := json.Marshal(mcpToolResult)
+		if err != nil {
+			return "", fmt.Errorf("failed to serialize tool result: %w", err)
+		}
+
+		anthropicToolResults = append(anthropicToolResults, anthropic.NewToolResultBlock(
+			toolUseBlock.ID,
+			string(resultJSON),
+			false,
+		))
+	}
+
+	// Append tool responses to message history
+	messages = append(messages, anthropic.NewUserMessage(anthropicToolResults...))
+
+	// Make another API call with tool results
+	response, err = c.anthropic.Messages.New(ctx, anthropic.MessageNewParams{
+		Model:     anthropic.ModelClaude3_7SonnetLatest,
+		MaxTokens: 1024,
+		Messages:  messages,
+	})
+	if err != nil {
+		return "", fmt.Errorf("anthropic API request with tool results failed: %w", err)
+	}
+
+	// Collect text from final response
+	for _, block := range response.Content {
+		switch b := block.AsAny().(type) {
+		case anthropic.TextBlock:
+			finalText = append(finalText, b.Text)
+		}
+	}
+
+	return strings.Join(finalText, "\n"), nil
+}
+
+func (c *MCPClient) ChatLoop(ctx context.Context) error {
+	fmt.Println("\nMCP Client Started!")
+	fmt.Println("Type your queries or 'quit' to exit.")
+
+	scanner := bufio.NewScanner(os.Stdin)
+
+	for {
+		fmt.Print("\nQuery: ")
+		if !scanner.Scan() {
+			break // EOF
+		}
+
+		query := strings.TrimSpace(scanner.Text())
+		if strings.EqualFold(query, "quit") {
+			break
+		}
+		if query == "" {
+			continue
+		}
+
+		response, err := c.ProcessQuery(ctx, query)
+		if err != nil {
+			fmt.Printf("\nError: %v\n", err)
+			continue
+		}
+
+		fmt.Printf("\n%s\n", response)
+	}
+
+	return scanner.Err()
+}
+
+func (c *MCPClient) Cleanup() error {
+	if c.session != nil {
+		if err := c.session.Close(); err != nil {
+			return fmt.Errorf("failed to close session: %w", err)
+		}
+		c.session = nil
+	}
+	return nil
+}
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Fprintln(os.Stderr, "Usage: go run main.go <server_script_or_binary> [args...]")
+		os.Exit(1)
+	}
+
+	serverArgs := os.Args[1:]
+
+	client, err := NewMCPClient()
+	if err != nil {
+		log.Fatalf("Failed to create MCP client: %v", err)
+	}
+
+	ctx := context.Background()
+
+	if err := client.ConnectToServer(ctx, serverArgs); err != nil {
+		log.Fatalf("Failed to connect to MCP server: %v", err)
+	}
+
+	if err := client.ChatLoop(ctx); err != nil {
+		log.Printf("ChatLoop error: %v", err)
+	}
+
+	if err := client.Cleanup(); err != nil {
+		log.Printf("Cleanup error: %v", err)
+	}
+}