mcp-api-test

An AI-native API testing engine that enables LLM agents to execute, validate, and reason about REST APIs using natural language or cURL inputs.

Unlike traditional testing frameworks, mcp-api-test exposes API testing as a first-class capability for AI agents rather than a developer-facing tool. LLM-powered clients invoke the run_test_api tool directly, making API validation a building block for autonomous coding agents, not a separate human-driven workflow.

It complements (rather than replaces) tools like pytest, Postman, and Playwright.

Breaking changes in v0.2.0. The server now runs on mcp 2.x, and the package layout moved from flat top-level modules to a proper mcp_api_test package. If you import internals directly, you may update to from mcp_api_test.server import .... MCP client configuration (OpenCode, Claude Desktop, Claude Code) is unaffected. See the changelog for details.

Use cases

• QA & test engineering: prompt an agent with natural language instead of crafting Postman requests
• Post-deployment regression: have an agent smoke-test critical paths after a deploy
• Quick validation: test an endpoint inline during a coding session
• CI/CD automation: agents validate deployments autonomously in pipelines

Token efficiency. Agents get deterministic, structured results in a single tool call instead of parsing raw curl output. Fewer tokens, fewer hallucinations.

Install

pip install mcp-api-test

Or from source:

git clone git@gitlab.com:ryaneatfood/mcp-api-testing.git
cd mcp-api-testing
pip install -e .

Requires Python >= 3.10.

Quick start

Configure your MCP client to use the server. For OpenCode, add to opencode.json:

{
  "mcp": {
    "mcp-api-test": {
      "type": "local",
      "command": ["mcp-api-test"],
      "enabled": true
    }
  }
}

For Claude Desktop, add to claude_desktop_config.json:

{
  "mcpServers": {
    "mcp-api-test": {
      "command": "mcp-api-test"
    }
  }
}

Then prompt your agent:

"Test this API: curl -X POST https://api.example.com/v1/users -H 'Authorization: Bearer xxx' -d '{"name":"test"}', ensure status code is 201 and response contains 'id'"

The agent invokes run_test_api, validates against the expected contract, and returns structured pass/fail results.

Documentation

Full documentation is hosted on this page, and another way to navigate the docs:

• Getting Started: installation and client setup
• Usage: cURL mode, structured mode, assertions, response format
• Guides: troubleshooting, development, configuration
• Reference: full parameter reference

License

MIT