mcp-jest

What is mcp-jest?

mcp-jest is a testing framework for Model Context Protocol (MCP) servers – like Jest, but for MCP. It provides automated testing, instant feedback, and CI/CD integration for MCP servers built in any language.

How to use mcp-jest?

Install via npm install mcp-jest (or globally with npm install -g mcp-jest), then either call the mcpTest function from your code or use the mcp-jest CLI command with a server command and list of tools to test. For example: mcp-jest node ./server.js --tools search,email.

Key features of mcp-jest

• Dead simple API – one function call tests your entire server.
• Declarative testing – describe what to test, not how.
• Comprehensive coverage – connection, capability discovery, functional, and validation.
• CI/CD ready – works with GitHub Actions, Jenkins, and more.
• Fast execution – complete suites in under 500ms.
• Zero dependencies beyond the official MCP SDK.
• Flexible usage – library, CLI, config files, TypeScript support.

Use cases of mcp-jest

• Development: test changes instantly during development.
• CI/CD: automated testing in build pipelines.
• Deployment: verify servers work before going live.
• Monitoring: regular health checks in production.
• Documentation: ensure examples actually work.

FAQ from mcp-jest

What runtime does mcp-jest require?

Node.js 18+ (for ESM and modern features) and any MCP server implementing the Model Context Protocol. TypeScript 5+ is optional for full type safety.

Does mcp-jest work with MCP servers in any language?

Yes, as long as the server follows the MCP standard. The README shows examples with Node.js and Python servers.

Can I use mcp-jest in my existing test suite?

Yes, you can import mcp-jest as a library and integrate it with test runners like Jest, Vitest, or Mocha.

How do I test a specific tool's arguments and results?

Pass tool definitions with args and an expect function to mcpTest. The function receives the tool result and should return a boolean or throw.

What is the connection timeout and how can I adjust it?

The default timeout is not specified, but you can increase it using the --timeout CLI flag (e.g., --timeout 60000 for 60 seconds).