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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), yet the description still adds real value: it never pays, never sends bad params, is rate-limited to 20/day/network, cached 24h, and results are private to the caller. It omits error behavior for non-x402 or unreachable URLs, keeping it short of a 5.

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?

Dense and front-loaded: purpose, return shape, behavior guarantees, and limits all arrive in two compact sentences. The trailing 'Grades are returned only to you' is slightly oblique but still earns its place as a privacy note.

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 usefully sketches the return payload ({score, grade, deductions[{code,points,fix}]}) and states cost, quota, and caching. Reasonably complete for a one-parameter read tool; failure modes and what 'grade' means are the remaining gaps.

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% with a clear description of the single 'url' parameter, so the schema carries the load. The description adds only the implicit constraint that the endpoint should be one you run; no format or edge-case guidance beyond that. Baseline 3 applies.

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: returns a hygiene score with grade and deductions for a given x402 endpoint, and specifies it derives from normal unpaid requests. An agent can tell this is a scoring/diagnostic tool, though it never names how it differs from the closely related endpoint_report or endpoint_spot_check siblings.

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?

'for an endpoint you run' implies ownership scope, and the rate/cache limits hint at intended usage, but there is no explicit when-to-use or when-not-to-use versus endpoint_report, endpoint_spot_check, or lookup. The agent must infer selection from the sibling names alone.

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