MCP

This server gives an agent read-only access to the Caplane lien registry on Arc Testnet. Every answer carries a receipt — endpoint, block height, call data and raw result — so it can be replayed against any node without trusting this server.

A lien id cannot be derived from a receivable: the registry key is salted with a secret that never leaves the enclave. Ask about a lien id you were given, or enumerate by borrower address with liens_of_borrower. Encumbered means status is exactly active; a released lien and an id that was never written both answer false, so read the status alongside the boolean rather than trusting it alone.

Connecting

The server speaks MCP over Streamable HTTP at https://mcp.caplane.xyz/mcp — POST only. It is stateless by construction: no session id is issued and nothing is kept between requests, so a restart costs a client nothing. GET /health answers 200 ok; a browser Origin outside *.caplane.xyz and loopback is refused with 403.

Reference

get_lien

Every recorded term of one lien: who borrowed, how much in USDC base units, at what rate in basis points, when it was recorded and when it expires. Carries a receipt that replays the reads against any node.

Input: lienId — the 32-byte lien id, as 0x-prefixed hex.

Reads the same three calls as lienOf, batched into one request pinned to one block height (services/mcp/src/rpc.ts), and returns the decoded lien plus status (the named string, not the raw byte), encumbered, and the receipt.

is_encumbered

Whether a lien is currently active. Released and defaulted are terminal and free the receivable, so this answers false for them and for an id that was never written — read the status it returns alongside the boolean rather than trusting it alone.

Input: lienId — the 32-byte lien id, as 0x-prefixed hex.

Returns { lienId, encumbered, status, note, receipt }. See isEncumbered for the same distinction spelled out against the SDK.

liens_of_borrower

Every lien ever recorded for one borrower address, from the registry deployment block. This is the only question answerable without having been handed a lien id: it says how much a counterparty has already pledged and until when.

Input: borrower — the 20-byte borrower address, as 0x-prefixed hex. fromBlock — optional decimal block height to start from; defaults to the deployment block.

Returns { borrower, fromBlock, endpoint, note, liens }, where liens is the same shape liensOf resolves to. The note flags that this is assembled from LienRecorded logs against one endpoint, so an endpoint that omitted an event would show less pledged than there actually is.

registry_identity

The chain, the registry address, the hash of its deployed code, and the workflow name it has frozen as an immutable — so a caller can check it is reading the real registry rather than taking this server's word for the address.

No input.

Returns { chainId, registry, codeHash, codeBytes, workflowName, workflowOwner, matchesFrozenIdentity }. matchesFrozenIdentity compares the live workflowName against the deployments constant this server was built with — false means the deployed workflow has moved and the address book is stale.

explain_rejection

What a SubmissionRejected reason code means. Reads nothing: the codes are fixed in the frozen interface, and the registry emits a bare uint8 with no enum behind it.

Input: code — the reasonCode from a SubmissionRejected event.

Returns { code, reason }. The full table of codes is the SDK's RejectReason reference.