go-sdk

The MCP Go SDK provides a set of packages to build MCP clients and servers in Go. With the mcp.Server abstraction, you can define and expose tools that can be invoked by MCP clients over a transport (such as standard input/output, a socket, or a custom protocol). Tools are functions that take a request, input payload, and return a result along with an output payload. The SDK includes core mcp, jsonrpc (for custom transports), and authentication primitives to support OAuth flows. To start a server, create an mcp.Server, register tools using mcp.AddTool, and run it over a transport like StdioTransport or a custom transport you implement. Clients can then connect to the server via the corresponding transport, call tools by name, provide arguments, and receive results or errors. The examples demonstrate a minimal server with a single tool and a sample client that connects over stdin/stdout, illustrating the typical workflow of defining tool inputs/outputs, wiring a server, and performing tool invocations over MCP. If you need authentication or advanced transport customization, you can leverage the auth and jsonrpc packages to implement OAuth primitives or a bespoke transport layer while preserving MCP semantics.

Prerequisites:

• Go 1.20+ installed and available on PATH
• A working Go workspace or module-aware project setup

Installation steps:

1. Create or navigate to your Go module/project
2. Pull the MCP Go SDK module go get github.com/modelcontextprotocol/go-sdk
3. Build or run an example server (adjust paths to your project structure) go run ./cmd/server/main.go

Optional: if you want to run tests or examples that rely on transport implementations, ensure your GOPATH/module mode is configured as your project requires.

Notes and tips:

• The SDK is modular; use mcp.Server for server composition, and mcp.AddTool to expose tools. Each tool has a function signature to handle requests and produce outputs.
• transports: The SDK includes StdioTransport for stdin/stdout and CommandTransport for spawning a separate process; you can implement additional transports by conforming to the MCP transport interface.
• Authentication: If you require OAuth or protected resources, explore the auth and oauthex packages for primitives and extensions.
• Environment variables: Consider MCP_LOG_LEVEL for logging verbosity and MCP_BIND_ADDR / MCP_PORT for binding the server network address when using network transports.
• Version compatibility: The Go SDK targets specific MCP spec versions; ensure client implementations align with the MCP spec version you intend to support.
• If you run into module resolution issues, ensure module mode is enabled (GO111MODULE=on) and your go.mod declares the correct module path.