Frequently Asked Questions

MCP Jest is the first automated testing framework specifically designed for Model Context Protocol (MCP) servers. It allows developers to write and run tests for their MCP servers, similar to how Jest works for JavaScript applications. MCP Jest enables automated testing, CI/CD integration, snapshot testing, and supports multiple transport protocols including stdio, HTTP streaming, and SSE.

Model Context Protocol (MCP) is an open standard introduced by Anthropic that enables AI assistants like Claude and ChatGPT to connect with external tools, data sources, and services. MCP servers expose tools, prompts, and resources that AI systems can use to perform tasks like searching databases, calling APIs, or executing code.

MCP Jest was created by Harsh Joshi. It is open source under the MIT license and free to use in both commercial and open source projects.

Yes, MCP Jest is completely free and open source under the MIT license. You can use it in commercial projects, open source projects, and personal projects without any cost or licensing fees.

MCP Jest requires Node.js version 18 or higher. This is because it uses modern JavaScript features and the MCP SDK that require Node.js 18+.

You can install MCP Jest globally using npm: `npm install -g mcp-jest`. For local installation in your project, use `npm install mcp-jest` or `npm install --save-dev mcp-jest`. Global installation is recommended for CLI usage, while local installation is better for programmatic usage in test files.

After installing MCP Jest globally, run `mcp-jest node ./your-server.js --tools tool1,tool2` where `./your-server.js` is the path to your MCP server and `tool1,tool2` are the names of tools you want to test. MCP Jest will automatically connect to your server, discover tools, run tests, and report results.

No, MCP Jest works out of the box with zero configuration. Simply point it at your MCP server and specify which tools to test. However, you can optionally create a configuration file (mcp-jest.config.json) for more advanced setups with custom timeouts, reporters, or test patterns.

Yes, MCP Jest supports multiple transport protocols. Use `--transport streamable-http --url http://localhost:3000` to test HTTP streaming servers, or `--transport sse` for Server-Sent Events. By default, MCP Jest uses stdio transport for local servers.

Snapshot testing in MCP Jest captures the output of your MCP tools and saves them to files. On subsequent test runs, MCP Jest compares the current output with the saved snapshots to detect unexpected changes. This is useful for regression testing. Use `--update-snapshots` to update snapshots when intentional changes are made.

Use the `--filter` option to run only tests matching a pattern: `mcp-jest node ./server.js --filter search`. You can also use `--skip` to exclude tests: `mcp-jest node ./server.js --skip experimental`. Both options support glob patterns.

Yes, MCP Jest can test all MCP primitives including tools, prompts, and resources. Specify which to test using the appropriate flags. By default, it auto-discovers and tests all available tools.

Yes, MCP Jest works seamlessly with GitHub Actions. Simply install it in your workflow and run your tests. Example: `npm install -g mcp-jest && mcp-jest node ./server.js --tools search`. MCP Jest returns proper exit codes (0 for pass, 1 for fail) for CI/CD integration.

Yes, MCP Jest works with any CI/CD system that can run npm commands, including GitLab CI, Jenkins, CircleCI, Travis CI, Azure Pipelines, and more. The installation and usage commands are the same across all platforms.

Add a test script to your package.json: `"scripts": { "test:mcp": "mcp-jest node ./server.js --tools search,calculate" }`. Then run it with `npm run test:mcp`. This makes it easy to run tests locally and in CI/CD pipelines.

Yes, MCP Jest provides a programmatic API that integrates with any JavaScript test framework including Jest, Vitest, and Mocha. Import MCPTester from mcp-jest and use it in your test files to connect to MCP servers, call tools, and make assertions.

Yes, MCP Jest is written in TypeScript and provides full type definitions. You can use it in TypeScript projects with full type safety and IntelliSense support in your IDE.

The MCPTester class provides methods like connect(), disconnect(), listTools(), callTool(name, args), listPrompts(), getPrompt(name), listResources(), and readResource(uri). Create a tester instance with your server config, connect, run tests, and disconnect.

Increase the timeout using `--timeout <ms>`. The default timeout is 30000ms (30 seconds). For slow servers or operations, try `--timeout 60000` for 60 seconds. Also ensure your MCP server is starting properly and responding to requests.

Ensure your MCP server properly implements the tools/list method and returns the tools you expect. Verify the tool names match exactly what you are specifying in --tools. Use `--verbose` to see detailed output about tool discovery.

Use the `--verbose` flag to see detailed output including server logs, request/response data, and error messages. You can also use MCP Inspector for interactive debugging during development, then switch to MCP Jest for automated testing.

MCP Inspector is an interactive debugging tool for manual testing and exploration of MCP servers. MCP Jest is an automated testing framework designed for CI/CD and regression testing. Use MCP Inspector during development to explore your server, and MCP Jest to automate testing in your pipeline.

Manual testing is time-consuming, error-prone, and cannot be integrated into CI/CD pipelines. MCP Jest provides automated, repeatable tests that run in seconds, catch regressions automatically, and block broken deployments. It saves hours of manual testing effort.

Yes, they complement each other. Use MCP Inspector during development for interactive debugging and exploration. Use MCP Jest for automated testing in your CI/CD pipeline and for regression testing.