If you’re testing MCP traffic and need something deterministic for CI, Laurentiu on our engineering team built and open-sourced two tools.
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Mock MCP Server. Go, in-memory, sub-second startup, 15 pre-configured tools, four prompts, three resources. Listens on localhost:7878/mcp. Drops into Docker Compose. Connects to Claude Desktop or Claude Code with a small config tweak.
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Mock MCP Client. An LLM-free client that runs three ways: CLI for shell invocation, HTTP server for Python tests, or Go library to import straight into your test suite.
Together they give you a full round-trip (client → gateway → server) for tests that don’t need real MCP infra or a live model in the loop.
Repos:
- GitHub - TykTechnologies/tyk-mock-mcp-server: This is an MCP mock server, that we are using extensively in testing our MCP capabilities · GitHub
- GitHub - TykTechnologies/tyk-mock-mcp-client: Mock mcp client to be used with integration tests · GitHub
Full story behind the build: How integration testing led me to create theTyk mock MCP server
Would be good to hear what you use them for.