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: 285 entries (152 stat checks, 133 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, claim URL and stale flag, or match: none.
verify_text(text, max_statements?)
Paste a whole draft (up to 20,000 characters). Every sentence with a number gets its own row: matched (with verdict, safe rephrasing and URL), possible, or not_in_database.
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. stale: true means we last opened the source more than 180 days ago. A verdict describes how a number is sourced and quoted, not whether the underlying idea is true.

Agent skill: stat-check

A ready-made stat-check SKILL.md (Claude Agent Skills format; also works as custom instructions in other agents) that describes when and how to check every number in marketing content with this server or the JSON API, and how to word the result. Download stat-check skill (.zip)

Connect

{
  "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)

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: hello@groundedkit.com. More: agent guide and free SKILL.md template.