@gblin-protocol/mcp-server

verify_gblin_authorization

Read-onlyIdempotent

Validate a signed GBLIN authorization before spending gas: recover the signer, check EIP-712/ERC-1271, nonce, validity window, and payer balance, then return a settle verdict or failure reason.

Instructions

Check a signed GBLIN authorization against the chain before spending gas on it. Recovers the signer from the EIP-712 digest (and asks the wallet itself through ERC-1271 when the payer is a contract), then checks the validity window against on-chain time, whether the nonce has already been used or cancelled, and whether the payer still holds the amount. Returns a verdict and the ready calldata when it would settle, the failing reason when it would not. This is the same set of checks an x402 facilitator runs, so a 'would_settle' verdict here means the payment is good to carry.

Input Schema

TableJSON Schema

Name	Required	Description
`method`	No	Which method the signature was produced for. Default 'receive'.
`signature`	Yes	The signature produced by the payer's wallet, 0x-prefixed.
`authorization`	Yes	The authorization object: from, to, value, validAfter, validBefore, nonce.

Output Schema

TableJSON Schema

Name	Required	Description
`amount`	No
`checks`	Yes
`digest`	No
`method`	Yes
`source`	No
`submit`	No	Calldata and who may submit it, or null when it would not settle.
`failures`	Yes	Reasons it would not settle; empty when it would.
`would_settle`	Yes	True only if the token would accept this authorization now.

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.1.5Oct 1, 2026

TDQS

A4.4/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly/idempotent/non-destructive, but the description adds substantial behavioral detail beyond them: EIP-712 signer recovery, the ERC-1271 contract-payer path, the validity-window/nonce/payer-balance checks, and the dual return shape (verdict + calldata vs. failing reason). This is exactly the extra context the annotations cannot carry.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Four sentences, front-loaded with the core action, then the mechanism, then the return contract, then the trust framing. Dense but each sentence carries information; only the final x402 sentence is arguably optional.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given an output schema exists, return values need not be explained, yet the description still clarifies the verdict semantics and calldata. Combined with the fully covered input schema and safety annotations, an agent has everything needed to call and interpret the tool correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% and the schema already documents each parameter (method enum, signature format, authorization fields). The description reinforces concepts like the digest and nonce but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource ('Check a signed GBLIN authorization against the chain') and clarifies it is a pre-flight verification distinct from sibling tools like prepare_gblin_payment and relay_gblin_payment. An agent can immediately tell this validates rather than executes a payment.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It clearly states when to use it ('before spending gas on it') and gives the operative condition for the verdict ('would_settle' means the payment is good to carry). It stops short of explicitly naming alternative siblings or when-not-to-use cases, so it is not a full 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.