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

With zero annotations the description carries the full burden and does so well: it declares the tool is free, has no side effects, touches no relay, reads expiry from the grant itself, and consults only the patron's revocation watermark. These are exactly the behavior facts an agent needs and cannot get from the schema or 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?

Efficient and front-loaded — the core purpose leads, then the motivating scenario, then the safety profile. The middle 'Mirrors check_oauth_status' sentence is slightly indirect and line-wrapped, but every sentence earns its place.

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?

An output schema exists, so return values need not be explained, and the description covers cost, side effects, data sources, and the motivating use case. It could note whether expiry/revocation results are the only outcomes, but nothing an agent needs to call it correctly is missing.

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 description coverage is 100%, so both parameters (dpop_token, patron_npub) are already fully documented in the schema; the description reinforces dpop_token's role by describing the token as the thing the next paid call will accept. Baseline 3 is appropriate since the schema does the heavy lifting and no format/syntax detail is added.

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 and resource — 'Check whether a proof grant is still valid' — and frames it inside the npub-proof flow, explicitly distinguishing it from the write-side sibling receive_npub_proof. An agent can tell this is a validation/read check, not a grant-issuing call.

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 concrete decision context: ask before 'burning credits on a guaranteed failure' on the next paid call, and names the analogous tool check_oauth_status. It does not enumerate when-not-to-use or name an alternative validator, but the triggering condition is clear.

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