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| 1 | +# Genkit MCP Plugin |
| 2 | + |
| 3 | +Model Context Protocol (MCP) integration for Go Genkit - connect to MCP servers and expose Genkit tools as MCP servers. |
| 4 | + |
| 5 | +## GenkitMCPClient - Single Server Connection |
| 6 | + |
| 7 | +Connect to and use tools/prompts from a single MCP server: |
| 8 | + |
| 9 | +```go |
| 10 | +package main |
| 11 | + |
| 12 | +import ( |
| 13 | + "context" |
| 14 | + "log" |
| 15 | + |
| 16 | + "github.com/firebase/genkit/go/genkit" |
| 17 | + "github.com/firebase/genkit/go/plugins/mcp" |
| 18 | +) |
| 19 | + |
| 20 | +func main() { |
| 21 | + ctx := context.Background() |
| 22 | + g, _ := genkit.Init(ctx) |
| 23 | + |
| 24 | + // Connect to the MCP everything server |
| 25 | + client, err := mcp.NewGenkitMCPClient(mcp.MCPClientOptions{ |
| 26 | + Name: "everything-server", |
| 27 | + Stdio: &mcp.StdioConfig{ |
| 28 | + Command: "npx", |
| 29 | + Args: []string{"-y", "@modelcontextprotocol/server-everything"}, |
| 30 | + }, |
| 31 | + }) |
| 32 | + if err != nil { |
| 33 | + log.Fatal(err) |
| 34 | + } |
| 35 | + |
| 36 | + // Get specific tools from the everything server |
| 37 | + echoTool, err := client.GetTool(ctx, g, "echo") |
| 38 | + if err != nil { |
| 39 | + log.Fatal(err) |
| 40 | + } |
| 41 | + |
| 42 | + addTool, err := client.GetTool(ctx, g, "add") |
| 43 | + if err != nil { |
| 44 | + log.Fatal(err) |
| 45 | + } |
| 46 | + |
| 47 | + // Get specific prompts from the everything server |
| 48 | + simplePrompt, err := client.GetPrompt(ctx, g, "simple_prompt") |
| 49 | + if err != nil { |
| 50 | + log.Fatal(err) |
| 51 | + } |
| 52 | + |
| 53 | + // Get all available tools |
| 54 | + tools, err := client.GetActiveTools(ctx, g) |
| 55 | + if err != nil { |
| 56 | + log.Fatal(err) |
| 57 | + } |
| 58 | + |
| 59 | +} |
| 60 | +``` |
| 61 | + |
| 62 | +## GenkitMCPManager - Multiple Server Management |
| 63 | + |
| 64 | +Manage connections to multiple MCP servers: |
| 65 | + |
| 66 | +```go |
| 67 | +package main |
| 68 | + |
| 69 | +import ( |
| 70 | + "context" |
| 71 | + "log" |
| 72 | + |
| 73 | + "github.com/firebase/genkit/go/genkit" |
| 74 | + "github.com/firebase/genkit/go/plugins/mcp" |
| 75 | +) |
| 76 | + |
| 77 | +func main() { |
| 78 | + ctx := context.Background() |
| 79 | + g, _ := genkit.Init(ctx) |
| 80 | + |
| 81 | + // Create manager with multiple servers |
| 82 | + manager, err := mcp.NewMCPManager(mcp.MCPManagerOptions{ |
| 83 | + Name: "my-app", |
| 84 | + MCPServers: map[string]mcp.MCPClientOptions{ |
| 85 | + "everything": { |
| 86 | + Name: "everything-server", |
| 87 | + Stdio: &mcp.StdioConfig{ |
| 88 | + Command: "npx", |
| 89 | + Args: []string{"-y", "@modelcontextprotocol/server-everything"}, |
| 90 | + }, |
| 91 | + }, |
| 92 | + "filesystem": { |
| 93 | + Name: "fs-server", |
| 94 | + Stdio: &mcp.StdioConfig{ |
| 95 | + Command: "npx", |
| 96 | + Args: []string{"@modelcontextprotocol/server-filesystem", "/tmp"}, |
| 97 | + }, |
| 98 | + }, |
| 99 | + }, |
| 100 | + }) |
| 101 | + if err != nil { |
| 102 | + log.Fatal(err) |
| 103 | + } |
| 104 | + |
| 105 | + // Connect to new server at runtime |
| 106 | + err = manager.ConnectServer(ctx, "weather", mcp.MCPClientOptions{ |
| 107 | + Name: "weather-server", |
| 108 | + Stdio: &mcp.StdioConfig{ |
| 109 | + Command: "python", |
| 110 | + Args: []string{"weather_server.py"}, |
| 111 | + }, |
| 112 | + }) |
| 113 | + if err != nil { |
| 114 | + log.Fatal(err) |
| 115 | + } |
| 116 | + |
| 117 | + // Temporarily disable/enable servers |
| 118 | + manager.DisableServer("filesystem") |
| 119 | + manager.EnableServer("filesystem") |
| 120 | + |
| 121 | + // Disconnect server |
| 122 | + manager.DisconnectServer("weather") |
| 123 | + |
| 124 | + // Get tools from all active servers |
| 125 | + tools, err := manager.GetActiveTools(ctx, g) |
| 126 | + if err != nil { |
| 127 | + log.Fatal(err) |
| 128 | + } |
| 129 | +} |
| 130 | +``` |
| 131 | + |
| 132 | +## GenkitMCPServer - Expose Genkit Tools |
| 133 | + |
| 134 | +Turn your Genkit app into an MCP server: |
| 135 | + |
| 136 | +```go |
| 137 | +package main |
| 138 | + |
| 139 | +import ( |
| 140 | + "context" |
| 141 | + "log" |
| 142 | + |
| 143 | + "github.com/firebase/genkit/go/genkit" |
| 144 | + "github.com/firebase/genkit/go/plugins/mcp" |
| 145 | + "github.com/firebase/genkit/go/ai" |
| 146 | +) |
| 147 | + |
| 148 | +func main() { |
| 149 | + ctx := context.Background() |
| 150 | + g, _ := genkit.Init(ctx) |
| 151 | + |
| 152 | + // Define some tools |
| 153 | + addTool := genkit.DefineTool(g, "add", "Add two numbers", |
| 154 | + func(ctx *ai.ToolContext, input struct{A, B int}) (int, error) { |
| 155 | + return input.A + input.B, nil |
| 156 | + }) |
| 157 | + |
| 158 | + multiplyTool := genkit.DefineTool(g, "multiply", "Multiply two numbers", |
| 159 | + func(ctx *ai.ToolContext, input struct{X, Y int}) (int, error) { |
| 160 | + return input.X * input.Y, nil |
| 161 | + }) |
| 162 | + |
| 163 | + // Option 1: Auto-expose all tools |
| 164 | + server := mcp.NewMCPServer(g, mcp.MCPServerOptions{ |
| 165 | + Name: "genkit-calculator", |
| 166 | + Version: "1.0.0", |
| 167 | + }) |
| 168 | + |
| 169 | + // Option 2: Expose specific tools only |
| 170 | + server = mcp.NewMCPServer(g, mcp.MCPServerOptions{ |
| 171 | + Name: "genkit-calculator", |
| 172 | + Version: "1.0.0", |
| 173 | + Tools: []ai.Tool{addTool, multiplyTool}, |
| 174 | + }) |
| 175 | + |
| 176 | + // Start MCP server |
| 177 | + log.Println("Starting MCP server...") |
| 178 | + if err := server.ServeStdio(ctx); err != nil { |
| 179 | + log.Fatal(err) |
| 180 | + } |
| 181 | +} |
| 182 | +``` |
| 183 | + |
| 184 | +## Testing Your Server |
| 185 | + |
| 186 | +```bash |
| 187 | +# Run your server |
| 188 | +go run main.go |
| 189 | + |
| 190 | +# Test with MCP Inspector |
| 191 | +npx @modelcontextprotocol/inspector go run main.go |
| 192 | +``` |
| 193 | + |
| 194 | +## Transport Options |
| 195 | + |
| 196 | +### Stdio (Standard) |
| 197 | +```go |
| 198 | +Stdio: &mcp.StdioConfig{ |
| 199 | + Command: "uvx", |
| 200 | + Args: []string{"mcp-server-time"}, |
| 201 | + Env: []string{"DEBUG=1"}, |
| 202 | +} |
| 203 | +``` |
| 204 | + |
| 205 | +### SSE (Web clients) |
| 206 | +```go |
| 207 | +SSE: &mcp.SSEConfig{ |
| 208 | + BaseURL: "http://localhost:3000/sse", |
| 209 | +} |
| 210 | +``` |
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