clearsigned-mcp

# clearsigned-mcp An MCP server that gives any agent a `verify_claim` tool: calibrated claim verification against live web evidence, paid per call over x402 ($0.05 USDC on Base), with an Ed25519-signed receipt the server verifies offline against Clearsigned's pinned published key before your agent sees it. ## Tools | Tool | Paid? | What it returns | |---|---|---| | `verify_claim(claim, evidence?)` | $0.05 USDC | `SUPPORTED` / `REFUTED` / `UNVERIFIABLE`, calibrated confidence (a measured realized rate), per-source stances, receipt id, settlement tx, `signature_verified_offline` | | `quote()` | free | the price an unpaid request is quoted right now, decoded from the 402 | | `service_status()` | free | what is serving, ledger height, published buyer counts | `UNVERIFIABLE` is a real answer, not an error: the engine abstains instead of guessing. The price never depends on the verdict; refunds exist only for failure to deliver. A request with no claim is refused locally, before any payment. ## Install ```bash pip install clearsigned-mcp # or: pipx install clearsigned-mcp export CLEARSIGNED_BUYER_KEY=0x… # an EVM key holding a little USDC on Base mainnet clearsigned-mcp # stdio transport ``` Claude Desktop / Claude Code / any MCP client: ```json { "mcpServers": { "clearsigned": { "command": "clearsigned-mcp", "env": { "CLEARSIGNED_BUYER_KEY": "0x…" } } } } ``` The key is used only to sign x402 payment authorizations from your own wallet. It is never sent to Clearsigned; the service sees the payment, not the key. ## How to check us - Pin the key at https://verify.clearsigned.com/pubkey; this server does, and refuses a receipt whose signature does not verify against it. - Walk the public hash-chained ledger at https://verify.clearsigned.com/ledger/verify; every paid receipt and its on-chain settlement are separate events joined on payer and nonce. - Read the live figures at https://clearsigned.com/quality (…