API Lab

API Lab MCP is an MCP server that lets you test, debug, and document APIs by chatting with Claude. It streamlines API testing directly from your development workflow, reducing tool-switching and enabling conversational, automatic test generation and documentation.

How to use

You use API Lab MCP by connecting it to an MCP client (Claude Code or Claude Desktop) and telling Claude what API you want to test. Start a test session, describe the endpoint, authentication, and assertions in natural language, and let Claude generate and run tests. You can test individual endpoints, run batch tests, validate responses with intelligent assertions, and auto-generate documentation from your test conversations. Switch between dev, staging, and prod environments to verify behavior across environments, or generate tests from OpenAPI specs to cover your API surface automatically.

How it works with your MCP client

Install the MCP server integration in your MCP client and add the API Lab MCP server to your list of available MCPs. Use your client’s command palette or UI to start a test session, then describe what you want to test. Claude will execute HTTP requests, track response times, and present results with suggested next steps and documentation snippets.

Additional usage tips

• Use natural language to specify authentication: for example, describe the token method, cookies, or OAuth flow you want Claude to apply. Claude can manage Bearer tokens, API keys, OAuth2, session cookies, and CSRF tokens as part of test setup.

• Leverage environment switching to validate behavior in dev, staging, and production without reconfiguring tests. Claude can reuse test conversations across environments with simple prompts.

• Generate documentation automatically: after test conversations, export or copy the resulting API docs and sample requests as part of your living API reference.

Examples of real-world use cases

Test a REST API endpoint by describing the action to Claude, then review the generated test and results in your MCP client.

Debug a failing endpoint by asking Claude to analyze headers, status codes, and responses to identify missing authentication or misconfigured parameters.

Generate tests from an OpenAPI/Swagger spec to automatically create a comprehensive test suite for all endpoints.

Security and environment considerations

Ensure access to your APIs is appropriately scoped for testing. Use environment separation (dev/stage/prod) to avoid cross-environment data leakage. Manage sensitive tokens and credentials through your MCP client’s secure storage and avoid exposing them in test conversations.

Performance and diagnostics

Monitor response times, payload sizes, and other metrics during tests. Use batch testing to run multiple endpoints in parallel or in sequence to surface bottlenecks and verify consistent performance across environments.

Available tools

test_http_endpoint

Test any HTTP endpoint with full customization: supports all HTTP methods, custom headers and authentication, request bodies, and returns detailed response data.

test_with_assertions

Advanced testing with intelligent validation: JSONPath, regex, status checks, timing, and custom rules.

test_with_session

Manage session-based authentication through cookies, CSRF tokens, and stateful flows across multiple requests.

batch_test

Run multiple API tests in parallel or in sequence with aggregated results for regression checks and health monitoring.

analyze_api_spec

Parse OpenAPI/Swagger specs to list endpoints, understand schemas, and draft test plans from specs.

generate_test_scenarios

Create comprehensive test suites from specifications, including edge and negative cases, exportable in multiple formats.