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

With no annotations, the description carries the full behavioral burden and does so: 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. That gives an agent strong confidence about safety and data sources.

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-loads the purpose in the first sentence and follows with usage, behavioral scope, and data source in four compact sentences. No sentence is redundant.

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?

The tool is simple, an output schema exists, and the description supplies purpose, usage timing, side-effect profile, and revocation-store semantics. Nothing needed to invoke 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 coverage is 100%, so the two parameters are already documented in the schema. The description adds some context by tying patron_npub to the revocation watermark, but it does not add syntax or validation meaning beyond the schema. Baseline 3 is appropriate.

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?

Opens with a specific verb+resource ('Check whether a proof grant is still valid') and adds the concrete decision it supports ('will my next paid call accept this dpop_token?'). It is distinguishable from proof acquisition siblings such as receive_npub_proof/request_npub_proof, though it does not explicitly contrast them.

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 when-to-use context: call this before a paid call to avoid burning credits on a known failure. It does not name explicit when-not conditions or an alternative sibling for comparison, but the usage scenario is unambiguous.

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