mcp-evidence-api

An MCP server that makes backend/API requests and packages request+response pairs as evidence — proving an endpoint works. Sibling project to mcp-evidence, which does the same thing for browser/UI flows; this one is for testing backend behavior with no browser involved (video/trace don't mean anything without a page, so this is a separate, much simpler tool rather than an extension of that one).

Generic and reusable: no assumptions about any particular API. You pass a baseUrl per session, and evidence is written into the consuming project's working directory at .evidence/<featureName>/<timestamp>/.

Install

Register with Claude Code

Per-user (available in every project):

claude mcp add --scope user evidence-api -- npx -y github:meovan07/mcp-evidence-api

Or per-project, add to .mcp.json:

{
  "mcpServers": {
    "evidence-api": {
      "command": "npx",
      "args": ["-y", "github:meovan07/mcp-evidence-api"]
    }
  }
}

This repo is public, so no GitHub credentials are needed on the machine running npx.

Consuming projects should add .evidence/ to their own .gitignore.

Related MCP server: mcp-server-apidebug

Tools

A session left open for 10 minutes with no tool calls is auto-finished. The server also flushes any open sessions on SIGINT/SIGTERM so evidence isn't lost if the process is killed mid-run.

Sensitive request/response headers (authorization, cookie, set-cookie, x-api-key, api-key, x-auth-token, proxy-authorization) are redacted before being written to disk. This only covers header names — if an endpoint echoes a secret back inside a JSON response body, that isn't redacted, since there's no reliable way to tell a secret-looking field from a normal one. Don't point this at endpoints that echo credentials in response bodies without being aware evidence files will contain them in plaintext.

Example

start_evidence_session({ featureName: "users api", baseUrl: "http://localhost:4000" })
  -> sessionId, evidenceDir

request({ sessionId, name: "create user", method: "POST", url: "/users", body: { name: "Ada" } })
request({ sessionId, name: "get user", method: "GET", url: "/users/1" })
finish_evidence_session({ sessionId, summary: "Users API create+fetch works" })

Resulting evidence directory:

.evidence/users-api/2026-07-08T08-41-21-754Z/
  requests.json
  manifest.json

requests.json is an array of full request/response records (method, url, headers, body, status, timing). manifest.json is a summary: request count and how many came back non-2xx.

Development

npm install
npm run build   # tsc -> dist/
npm run dev     # tsc --watch
npm start        # node dist/index.js