Exercise the interface.
Discover server capabilities and test tools, resources, and prompts through a command-line interface or JavaScript API.
← ALL WORK Test the tools.
MCP-Jest / Verify / Open source
Test the tools.
Trust the evidence.
MCP-Jest helps developers test the servers their agents depend on. Check tools, resources, and prompts through the Model Context Protocol, then bring those checks into your development workflow.
MIT LICENSEDTYPESCRIPTCLI + LIBRARY
How it works
From a tool call to a checked result.
Connect to your MCP server, exercise its capabilities, and compare the responses with your expectations. Keep the results available for review.
THE TEST PATH
01ConnectYour MCP server
02ExerciseTools & capabilities
03CheckDefined expectations
Reports · snapshots · CI results
What it gives you
Catch changes in behavior.
Use expectations and snapshots to check responses. Filter tests and use watch mode while you work on a server.
Make checks repeatable.
Run server checks in CI and review generated reports. Protocol validation adds another view of how a server behaves.
Quickstart
Put your server under test.
Use Node.js 18 or later and an MCP server you can run. Install the CLI, then point it at that server’s start command.
Read the documentationnpm install -g mcp-jestmcp-jest node ./server.js --tools searchReplace ./server.js with your server entrypoint and search with the tool you want to test. The documentation explains configuration files, expectations, snapshots, and CI setup.
Before you build
Understand the
boundaries.
What does MCP-Jest test?
It exercises an MCP server’s tools, resources, and prompts, and checks the responses against the tests you define. It also provides protocol validation and snapshot testing.
Does it prove an agent is correct?
No. Passing server tests is evidence about the behaviors covered by those tests. It does not prove that an agent will choose the right tool, reason correctly, or complete every task.
Which connections can I test?
The repository documents stdio, HTTP streaming, and SSE transports. See the transport guides for configuration details and examples for your server.
Can I use it in an existing pipeline?
Yes. Run the CLI or JavaScript API alongside your current checks. The repository includes CI examples and a GitHub Action, plus contribution and security guidance.
Help shape the work
Try it. Question it.
Make it better.
Explore the code, follow the setup guide, and share what you find. Questions and reproducible bug reports are useful contributions.