API Change Feed

npx add-mcp 'https://changefeed.anthonyzilar.workers.dev/mcp'

Try it: what changed since my version?

Add it to your coding agent

The quick check is free. Paid tools appear too; an agent with an x402 wallet can call them, others just use the free ones.

Claude Code

Run once in a terminal:

claude mcp add --transport http changefeed https://changefeed.dev/mcp

Cursor

Add to ~/.cursor/mcp.json (or.cursor/mcp.json in a project):

{
  "mcpServers": {
    "changefeed": {
      "url": "https://changefeed.dev/mcp"
    }
  }
}

VS Code

Add to.vscode/mcp.json:

{
  "servers": {
    "changefeed": {
      "type": "http",
      "url": "https://changefeed.dev/mcp"
    }
  }
}

Any HTTP agent

No install. Call:

GET https://changefeed.dev/v1/quick-check?package=express&from=4.21.0

Tell your agent when to use it

Agents call tools when their instructions say to. Paste this into CLAUDE.md, AGENTS.md or your Cursor rules:

Before writing or changing code that uses a third-party library or SDK, call the changefeed quick_check tool with the package name and the version this project uses (from package.json, requirements.txt or the lockfile). If it reports breaking changes or deprecations, call upgrade_check or read the release notes before writing code, and don't rely on memory for that library's API.

Pricing

Paid per call in USDC on Base through x402. No account, no key, no subscription. Errors and unknown packages are never charged.

HTTP	MCP tool	Price	Answers
GET /v1/quick-check	quick_check	free	Did anything break since my version? Verdict, counts and top headlines. About 20 a minute per client.
GET /v1/upgrade-check	upgrade_check	$0.01	Every breaking change, deprecation and security fix since your version, with the release-note sentence behind each.
GET /v1/changes	get_changes	$0.005	Change records for one API/SDK or all, filtered by date and kind.
GET /v1/digest	digest	$0.02	Everything breaking across all 60 sources since a date.
GET /v1/sources	list_sources	free	What we track and the package names to ask by.