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Evidence

Verifies signed receipts and creates counter-signed disclosure evidence for agent-commerce workflows.

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Install Evidence

Pick your client, then add it in one click or paste the config.

STDIONode.js
~/Library/Application Support/Claude/claude_desktop_config.json
claude_desktop_config.json
{
  "mcpServers": {
    "evidence": {
      "command": "npx",
      "args": [
        "-y",
        "tersign"
      ]
    }
  }
}

Settings → Developer → Edit Config, merge this into mcpServers, then fully quit and reopen Claude Desktop.

Automated check passed— started and listed 9 tools correctly (6d ago).

Overview

The evidence MCP server handles signed receipts, disclosure attestations, and dispute evidence through the Tersign ledger. It verifies receipt files locally or checks receipt digests against a ledger, while disclosure commands hash text locally before signing and submitting a record. Use it when an agent transaction needs independently verifiable evidence, a seller-bound chain of custody, or an evidence envelope for later disputes. The package also provides an x402 fetch-handler adapter that places receipt data in payment response headers.

Use cases

  • Verify seller-signed x402 receipts before accepting transaction evidence
  • Create timestamped disclosure attestations without sending the disclosure text
  • Attach refund and dispute references to a receipt digest
  • Add receipt evidence to x402 payment response headers
  • Inspect a receipt chain through the Tersign ledger

Key features

  • EIP-712 receipt verification
  • Per-seller hash chains with ledger counter-signatures
  • Local disclosure hashing and signing
  • x402 payment-response integration
  • Receipt and digest verification
  • Dispute and refund evidence references

Tools9

What Evidence lets your agent do. Expand a tool for its parameters.

Verified live~3.5k tokens of context

Security & health

What it can reach and how reliably it runs — from our own checks, not the maintainer’s claims.

ActiveLast checked 1d ago

Recent health check succeeded.

7/7 checks healthy over the last 44d

What it can do

From the 9 tools this server returned when we ran it; 9 declare their own safety hints.

Can delete or modify data · 1Handles credentials · 6Makes network requests · 7Read-only tools · 8
Network at startup3 connections
Files written at startup1
Install scriptsNone
npm provenanceSigned build
Package age97 days
Maintainers1

Observed 2026-10-16 in an isolated sandbox. A description of reach, not a security audit.

Supply-chain signal

No high-severity advisories surfaced by our automated scan.

Critical 0High 0Medium 0Low 0

Scanned 6d ago via OSV.dev · tersign (npm)

Adoption & maintenance

Factual signals from GitHub, npm, and our automated checks — not a rating.

GitHub stars1Stargazers on the source repository.
npm downloads2kPackage downloads in the last 30 days.
Last commit5d agoMost recent push to the default branch.
Availability100%Our rolling endpoint + install checks that succeeded.
Install checkPassedOur sandbox started it and listed its tools.
Tools exposed9Callable tools this server registers over MCP.
Directory activity1 viewsConfig copies, upvotes, and views on AllMCPs.

How Evidence works

What evidence MCP server does

The evidence MCP server supports evidence workflows around agent commerce rather than general-purpose data access. Tersign receipts use EIP-712 signatures and the x402 offer-and-receipt extension. The resulting payload receives a canonical keccak256 digest, is linked into a per-seller hash chain, and can receive a counter-signature from the Tersign ledger.

The evidence MCP server can verify a receipt supplied as JSON or identified by its digest. Local file verification recovers the signing address and can compare it with an issuer address supplied separately through --signer. Digest verification queries a ledger and reports that ledger’s counter-signed chain result; it does not re-verify the record locally.

Disclosure evidence is another supported workflow. A command digests disclosure text locally, signs the resulting record, and submits it for ledger counter-signing. This produces evidence that a disclosure was attested at a particular time, but it is not a compliance certification.

How it works

A seller signs a receipt, Tersign computes its digest, and the digest joins a seller-specific sequence where each entry refers to the previous one. The ledger counter-signs the entry. Chain commitments are submitted for Bitcoin anchoring on a six-hour schedule; newer anchors cover the complete preceding prefix, while earlier anchors identify the head record they cover.

Disclosure text stays local during digest creation; only the digest is sent. The first disclosure request can create a free signer-keyed account, subject to provisioning, quota, and rate limits. Refund records can point to the corrected record by digest, and disputes can attach objective reason codes. Party statements are kept separate behind an UNVERIFIED marker.

Setup and configuration

Install the JavaScript package with:

Terminal
npm i tersign

Signing keys are resolved from TERSIGN_SELLER_KEY, the macOS keychain entry named tersign-signer, or ~/.tersign/signer.key. A key file is created on first use when no earlier key is available. The withAssure() adapter can wrap an x402 fetch handler. With a configured ledger, it adds a seller receipt and a compliance-fields record to the base64 JSON payment response header while leaving the response body unchanged.

Tools and capabilities

The evidence MCP server’s documented command-line capabilities include:

  • Verify a receipt file or digest with npx tersign verify.
  • Compare a locally recovered signer with an issuer address using --signer.
  • Select another ledger with --ledger when checking a digest.
  • Create disclosure evidence with npx tersign disclose, including a medium and agent identifier.
  • Retrieve verification results over HTTP from the Tersign receipt verification endpoint.
  • Wrap x402 handlers with Assure and withAssure() to emit payment-response evidence.

Verification rejects malformed JSON structures, duplicate keys, non-integer numbers, non-canonical signatures, unsupported signed field types, and published development test keys. Exit status 0 indicates a valid result, 1 an invalid result, and 2 a usage error.

Limitations and notes

A receipt file checked without --signer is reported as having an unauthenticated signer. Signature recovery alone does not establish that the recovered address belongs to the issuer. Digest checks are ledger-reported and explicitly do not perform the local receipt verification performed for files.

Disclosure requests may fail when the signer is already attached to an API-key ledger account, provisioning limits are reached, or free-tier limits apply. If an x402 settlement network is unsupported or the ledger fails, withAssure() passes the paid response through without a receipt and sends the error to onError. Compliance-fields records are not counter-signed by the ledger; they are linked to their receipt by the seller’s signature.

Read the full README View source on GitHub

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Frequently Asked Questions about Evidence

evidence is an MCP server that connects agent-commerce workflows to the Tersign ledger for signed receipt verification and disclosure evidence. Its main capabilities include checking receipt files or digests, creating signed disclosure records, and supporting x402 payment responses with receipt and compliance-fields data.

Install the JavaScript package with `npm i tersign`.

Run `npx tersign verify <receipt.json | digest>`. Receipt files are checked locally; add `--signer` to compare the recovered signature address with an issuer address, or use `--ledger` to select a ledger for digest lookup.

The README identifies an MCP registry entry but does not name Cursor or describe a Cursor configuration.

The disclosure text is digested locally, so only its digest is sent to the ledger. The signer signs the resulting record, and the ledger counter-signs it into a per-signer chain.

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