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

Annotations already establish read-only, idempotent, non-destructive, closed-world behavior, and the description adds meaningful context on top: it is free, requires no account, and only accepts public/non-personal inputs. The draft-and-may-change disclaimer is a useful stability signal not present in annotations.

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

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

Front-loaded with the triggering condition and then compressed into the returned checks and constraints. Every clause carries information; the semicolon-joined constraints are dense but not padded.

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

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

With no output schema, the description compensates by naming the returned signals (missing fields, receipt_id match, signature validity). For a two-parameter, nested-object input with full schema coverage and rich annotations, this is sufficient, though the accepted receipt variants could be clarified.

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

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

Schema coverage is 100% and the schema descriptions already explain the public_key formats (raw base64url vs JWK) and the GAIP default key fallback, leaving little for the description to add. The description merely restates that public_key is optional and does not elaborate on the accepted receipt shapes.

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

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

States a specific verb+resource ('Check an x402 SAR receipt') and enumerates exactly what is evaluated: missing fields, receipt_id/core match, and signature validity. It does not explicitly distinguish itself from the sibling verify_gaip_receipt, so an agent could wonder which verifier applies.

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

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

Gives a clear trigger condition ('when handed an x402 SAR-shaped receipt') plus the shape caveat ('draft proposal shape; may change') and the input constraints ('must be public and non-personal'). No named alternative or exclusion against verify_gaip_receipt, which keeps it short of a 5.

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