Surface Contract MCP Server

Install Surface Contract MCP server

claude mcp add --transport http surface-contract https://penny-surface-contract.penny-mcamp.workers.dev/mcp

{
  "mcpServers": {
    "surface-contract": {
      "url": "https://penny-surface-contract.penny-mcamp.workers.dev/mcp"
    }
  }
}

{
  "mcpServers": {
    "surface-contract": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://penny-surface-contract.penny-mcamp.workers.dev/mcp"
      ]
    }
  }
}

{
  "servers": {
    "surface-contract": {
      "type": "http",
      "url": "https://penny-surface-contract.penny-mcamp.workers.dev/mcp"
    }
  }
}

{
  "mcpServers": {
    "surface-contract": {
      "serverUrl": "https://penny-surface-contract.penny-mcamp.workers.dev/mcp"
    }
  }
}

Context tax

Connecting this server adds ~1,338 tokens of tool definitions to every model turn (moderate, 7 tools). Measured 2026-10-19 via its hosted endpoint; o200k tokenizer, worst case for clients that load all tools up front. How we measure

Input prices as of 2026-10-06. Excludes your own prompt and output.

Tools (7)

• contribute_discrepancy377 tok

  Report a platform behaviour that contradicts a published claim, or a new claim, with evidence. One-line call: POST /v1/contribute with {contractId, kind, statement, evidence[], reporter, observedAt}. Stored as pending; a published contract is never changed without independent verification. A contractId no published contract serves is accepted as a NEW-PLATFORM PROPOSAL: the 202 body carries contractExists:false (with proposal:true, proposedContractId and proposedHost), it is listed distinctly at GET /v1/contributions, and it stays pending until a second party reproduces it - it never creates o

• preflight_mcp_server275 tok

  Run the anonymous MCP handshake against ANY https MCP endpoint you name, right now, and get back a verdict (open / refused / unreachable / initialize-transport-error), the shape of any refusal body, whether the server is stateful (sets Mcp-Session-Id), how many tools tools/list returns, and the guard clauses that follow. Use it before wiring an MCP server into your own config. Pass `urls` (up to 5) to check a whole mcp.json in one call. When the endpoint refuses, it also reports whether the refusal advertises a credential path (an RFC 9728 resource_metadata pointer) and whether that pointer re

• prepay_check258 tok

  Check an x402 route BEFORE you pay it. GET /v1/prepay?url=<the route> makes ONE unpaid GET with no payment header and no credential, and returns one row: the measured HTTP status, the parsed x402 v2 challenge (scheme / network / asset / amount / payTo), whether that challenge is schema-valid exact-on-Base, and whether its payTo and price agree with the seller's own card (pass `card` to read that card with one more unpaid GET). No payment is made, no credential is sent, no redirect is followed, and a transport failure on our side is reported as unknown rather than as a fact about the seller. Us

• get_integration_recipe94 tok

  Get a plain-text integration recipe for a platform: the order of operations to use it, and a guard clause for every behaviour we measured going wrong, each naming the contract claim behind it. Derived from the contract, so it cannot drift from it.

• get_surface_contract92 tok

  Get the machine-readable surface contract for a platform host (read/write semantics, pending states, rate limits, limits, idempotency, pagination completeness, data portability), each claim carrying its evidence and its verification status.

• verify_surface53 tok

  Run the anonymous conformance checks for a contract now and return verified / failed / unknown / manual / unsupported per claim.

• list_surface_contracts38 tok

  List the platform surface contracts published in Penny's free registry, with claim counts.

Freshness

Active — last maintenance signal 5d ago. The newest of the signals below sets the band.

1. Last commit (default branch)

   no data · GitHub

2. Latest release

   no data · GitHub

3. Package published

   no data · npm/PyPI

4. Registry entry updated

   2026-10-13 · 5d ago · official registry · v2026.10.13