Surface Contract: platform API behavior and x402 pre-payment checks

dev.workers.penny-mcamp.penny-surface-contract/surface-contractVersion 2026.10.22

Surface contracts: API behavior evidence, x402 pre-payment check, MCP server preflight

Status

Responds634 msNov 14, 2026, 14:29 UTCAnswered our handshake without sign-in.

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Last checked: Nov 14, 2026, 14:29 UTC
Latency: 634 ms
Remotes responding: 1 of 1
Sign-in: No sign-in
Hosting: Hosted outside the EU (detected)
Registry data as of: Nov 14, 2026, 22:14 UTC

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Connect

Streamable HTTP

https://penny-surface-contract.penny-mcamp.workers.dev/mcpResponds634 msNov 14, 2026, 14:29 UTC

No sign-in

Claude Code

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

Claude Desktop and claude.ai

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Settings > Connectors > Add custom connector
Name: surface-contract
Remote MCP server URL: https://penny-surface-contract.penny-mcamp.workers.dev/mcp

Cursor

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

VS Code

code --add-mcp '{"name":"surface-contract","type":"http","url":"https://penny-surface-contract.penny-mcamp.workers.dev/mcp"}'

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Tools

7 tools

Tools of Surface Contract: platform API behavior and x402 pre-payment checks
	Description		Read-only	Idempotent	Open world
`contribute_discrepancy`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 or mutates a contract. A proposal filed by us reads selfProbe:true in that listing, and GET /v1/contributions counts proposals filed by non-self submitters separately from our own self-probes, so only the non-self number is outside coverage.	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 or mutates a contract. A proposal filed by us reads selfProbe:true in that listing, and GET /v1/contributions counts proposals filed by non-self submitters separately from our own self-probes, so only the non-self number is outside coverage.	Not declared	Not declared	Not declared	Not declared
`get_integration_recipe`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 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.	Not declared	Not declared	Not declared	Not declared
`get_surface_contract`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.	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.	Not declared	Not declared	Not declared	Not declared
`list_surface_contracts`List the platform surface contracts published in Penny's free registry, with claim counts.	List the platform surface contracts published in Penny's free registry, with claim counts.	Not declared	Not declared	Not declared	Not declared
`preflight_mcp_server`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 resolves to a metadata document naming an authorization server, so you learn where a token would come from without writing that parsing yourself. No credential is sent, none is obtained, and none of their tools is ever called.	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 resolves to a metadata document naming an authorization server, so you learn where a token would come from without writing that parsing yourself. No credential is sent, none is obtained, and none of their tools is ever called.	Not declared	Not declared	Not declared	Not declared
`prepay_check`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. Use it to gate a payment decision on measured terms instead of on a seller's prose.	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. Use it to gate a payment decision on measured terms instead of on a seller's prose.	Not declared	Not declared	Not declared	Not declared
`verify_surface`Run the anonymous conformance checks for a contract now and return verified / failed / unknown / manual / unsupported per claim.	Run the anonymous conformance checks for a contract now and return verified / failed / unknown / manual / unsupported per claim.	Not declared	Not declared	Not declared	Not declared

Details

Registry status: Active
Published: Oct 22, 2026
Updated: Oct 22, 2026
Website: https://penny-surface-contract.penny-mcamp.workers.dev/⁠ (opens in a new tab)
Repository: Not given
Categories (suggested): Finance and paymentsSuggested categories are assigned automatically from the registry text and may be wrong. Verified operators can correct them.
GDPR: Not declared

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