mcp-postman-runner

Run the requests in a Postman collection folder — and get structured, assertion-level results back — straight from your AI assistant.

A Model Context Protocol (MCP) server that executes a folder of a Postman collection: it resolves {{variables}}, runs the collection + item pre-request scripts (so token-auth patterns work), fires each request, and evaluates the embedded `pm.test` scripts — then returns status, timing, body, and per-assertion pass/fail.

It replicates only the slice of newman needed for agent-driven API testing, with no runtime dependencies beyond the MCP SDK and zod.

🎯 Why use this

The Postman connector/API can create requests but can't run them. This server is the execution engine in a Jira → Postman → assess → comment workflow:

Jira ticket ─► derive test cases ─► create a Postman folder (named = ticket key) with pm.test scripts
   ─► run_folder (this MCP) ─► assess responses ─► comment results on the ticket

Supported AI assistants

Any MCP client — Claude Desktop, Claude Cowork, GitHub Copilot (VS Code), Cursor, Windsurf, etc.

✨ Features

• Folder execution — run every request in a folder, in order, sharing variables across the run.
• Auth that just works — collection/item pre-request scripts run (incl. pm.sendRequest), so a token fetched once flows to the rest of the folder.
• Assertion evaluation — the embedded pm.test scripts run via a minimal pm/expect sandbox; you get deterministic pass/fail per assertion.
• Structured output — status, time, response body (truncated), and assertion details for each request, ready for an agent to assess.
• Credential-less — holds no secrets; the caller passes the collection/environment JSON.
• Zero runtime deps — only @modelcontextprotocol/sdk and zod.

📋 Prerequisites

• Node.js >= 18 (uses the global fetch).
• Network access from wherever this runs to the API under test.
• A Postman collection (and optional environment) JSON — typically fetched via the Postman API/connector.

🚀 Quick start

Add to your MCP client config:

{
  "mcpServers": {
    "postman-runner": {
      "command": "npx",
      "args": ["-y", "mcp-postman-runner@latest"]
    }
  }
}

npx fetches and caches the package on first launch. CLI help: npx -y mcp-postman-runner@latest --help.

🛠️ Tools

All tools take the collection JSON (the collection object from the Postman API / connector's getCollection), and optionally an environment JSON.

run_folder / run_request result

{
  "summary": { "totalRequests": 9, "requestsErrored": 0, "assertionsTotal": 24, "assertionsFailed": 4, "anyFailure": true },
  "results": [
    {
      "name": "TC-01 Happy path", "method": "GET",
      "url": "https://api-dev.example.net/api/v2/countries/states/cities",
      "status": 200, "statusText": "OK", "timeMs": 142,
      "assertionsPassed": 3, "assertionsFailed": 0,
      "assertions": [ { "name": "status is 200", "passed": true, "error": null } ],
      "responseBody": "{ … }"   // truncated at 20k chars
    }
  ]
}

🔬 How it works

1. Variables — merges collection variables + environment values; resolves {{var}} (nested, iteratively).
2. Auth / pre-request — runs the collection-level then item-level pre-request scripts. pm.sendRequest is supported, so the common "POST the auth URL, store the token, reuse it" pattern works; the token is cached in the run's variables.
3. Request — builds the URL/headers/method, fires it with fetch (per-request timeout).
4. Assertions — runs the request's test script through a pm/expect sandbox and records each pm.test result.

Supported pm subset

pm.test, pm.expect (eql/equal/deep, true/false/null, have.property, at.most/least, above/below, within, include, oneOf, a/an, match, empty, negation via .not), pm.response.code/.json()/.text(), pm.environment & pm.variables get/set, and pm.sendRequest. See ARCHITECTURE.md for details.

🔒 Security

Credential-less by design; secrets in the passed environment are kept in memory for one run and never logged. Only run collections you trust — their pre-request/pm.test scripts execute in the server process. See SECURITY.md.

🤝 Contributing

See CONTRIBUTING.md. Uses Conventional Commits + semantic-release.

📜 License

MIT

🔗 Links

• Issues: https://github.com/tezaswiraj7222/mcp-postman-runner/issues
• MCP: https://modelcontextprotocol.io