MCP server & API for agents

GroundedKit runs a free, read-only Model Context Protocol server so an agent can check a marketing statistic before it repeats it. No key, no login, no tracking beyond standard Cloudflare logs. Data: 106 entries (72 stat checks, 34 reference facts), CC BY 4.0, last reviewed 2026-10-16.

Server URL

https://groundedkit.com/mcp

Transport: Streamable HTTP (JSON-RPC 2.0 over POST, JSON responses, stateless). Protocol versions 2025-11-25, 2025-06-18, 2025-03-26 and 2024-11-05. A plain GET on the URL returns a JSON description of the server.

Tools

check_stat(text): Paste a stat (or a paragraph). Returns the best match with verdict, confidence, primary source, what the source says, safe rephrasing and claim URL, or match: none.
search_claims(query, verdict?, limit?): Keyword search over all checked claims, optional verdict filter.
get_claim(id): Full record for one claim by slug or claim URL.
list_verdicts(): Verdict definitions, counts, confidence levels and dataset info.

All tools are read-only. A verdict describes how a number is sourced and quoted, not whether the underlying idea is true.

Connect

Claude Code: claude mcp add --transport http groundedkit https://groundedkit.com/mcp
Claude (web/desktop): Settings > Connectors > Add custom connector > paste the URL.
Cursor (~/.cursor/mcp.json), VS Code (.vscode/mcp.json, key servers) and most other clients:

{
  "mcpServers": {
    "groundedkit": {
      "type": "http",
      "url": "https://groundedkit.com/mcp"
    }
  }
}

Clients that only speak stdio can use a bridge such as npx mcp-remote https://groundedkit.com/mcp.

Raw example

curl -s https://groundedkit.com/mcp -H 'content-type: application/json' -H 'accept: application/json, text/event-stream' \
  -d '{"jsonrpc": "2.0", "id": 1, "method": "tools/call", "params": {"name": "check_stat", "arguments": {"text": "Influencer marketing returns $5.78 for every $1 spent"}}}'

JSON API (no MCP needed)

/api/claims.json: every claim (schema v1.1), JSON Schema
/api/claims/<id>.json: one claim, e.g. /api/claims/influencer-marketing-roi-5-78.json
/api/claims.csv, /llms.txt, /llms-full.txt
/server.json: MCP Registry metadata

CORS is open on the API and the MCP endpoint. Please cite the claim page URL when you use a result. Problems or a stat we should trace: [email protected]. More: agent guide and free SKILL.md template.