witnessd-mcp
MCP server for witnessd — a neutral third-party witness for the machine-readable web.
Give your agent the ability to create tamper-evident evidence: witnessd independently fetches any public URL or API endpoint, hashes and timestamps the response, archives it, and issues a signed certificate. Snapshot hashes are Merkle-batched hourly and anchored on Base, so certificates verify forever — by anyone, without trusting the operator.
Use it before transacting with a counterparty ("witness their published price/terms"), before acting on third-party data ("witness what the API returned"), or whenever a dispute might later hinge on what a URL said at a moment in time.
| Tool | Price | What it does |
|---|
witness_url | $0.02 | Independent fetch + hash + timestamp + archive of a URL right now; returns snapshot id + signed certificate |
get_certificate | free | Certificate for any snapshot id: manifest, Ed25519 signature, Merkle proof, Base anchor transaction |
retrieve_snapshot | $0.05 | The archived response body + certificate — works for any snapshot id, any payer (this is how third parties obtain evidence) |
Install
Claude Desktop / Cursor config:
{
"mcpServers": {
"witnessd": {
"command": "npx",
"args": ["-y", "witnessd-mcp"],
"env": {
"EVM_PRIVATE_KEY": "0x…"
}
}
}
}
Payment — two options
Set one of these environment variables:
EVM_PRIVATE_KEY — a wallet key holding USDC on Base. The server auto-pays each call via x402 (the buyer only signs; no ETH needed for gas). Use a small dedicated wallet, never your main one.WITNESSD_API_KEY — a prepaid credit key (buy a $1 pack via POST https://witnessd.vip/api/credits, x402-payable).
Optional: WITNESSD_URL to point at a different witnessd instance (default https://witnessd.vip).
Verify without trusting us
Certificates are self-verifying: leaf_hash = sha256(canonical-json(manifest)), Ed25519-signed, Merkle-proven into an hourly batch root anchored on Base (calldata 0x + wtns1 + root). Standalone checker: witnessd.vip/verify.js.
Privacy & scope
Certificates (hashes, timestamps, proofs) are public; archived content is delivered only to paying requesters and never republished. witnessd only witnesses what any stranger can see — no logins, no private networks, bodies ≤10 MB. Machine-readable service docs: llms.txt · openapi.json · /.well-known/x402.
MIT license.