mcp-go — Build MCP Servers in Go

Practical Notes

• Quickstart includes a calculator tool example you can run in <15 minutes
• The README contains multiple example sections (server/resources/tools/prompts/session management) you can copy incrementally

A Go-Native Pattern for Tool Design

Treat each MCP tool as a stable “function contract”:

• Keep inputs small and typed (string/number/enum) so the agent can call it reliably.
• Put your real side effects behind a thin validation layer.
• Prefer idempotent operations (safe retries) and provide clear error messages.

Once you have one tool, scale to a toolkit:

1. Add resources for read-only context (like listing projects or configs).
2. Add tools for side effects (create/update/apply).
3. Add prompts to encode standard operating procedures for your team.

That split (resources vs tools vs prompts) makes agent behavior easier to reason about and audit.

FAQ

Q: Is mcp-go only for servers? A: It’s primarily a server SDK; it helps you expose tools/resources/prompts to MCP clients.

Q: Do I need HTTP? A: No. The README quickstart uses stdio transport, which works with many clients.

Q: How do I keep tools safe? A: Validate inputs, keep side effects minimal, and prefer idempotent operations.