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

No annotations are present, so the description carries the full burden. It transparently covers bounded fetches, refusal of private addresses, per-target rate limiting, and the returned values (count, target, date). It doesn't explicitly mention auth or side effects, but the audit nature and constraints make it reasonably transparent.

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?

Two dense sentences with a clear structure: cost indicator ('Free'), action, constraints, and return value. No filler; every clause carries useful information, and the most important framing (free + decision use case) is front-loaded.

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 still explains what the result contains and how to act on it. For a single-parameter tool, it covers the workflow, safety constraints, and decision context sufficiently for an agent to invoke it correctly.

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% for the url parameter, so the baseline is 3. The description adds a meaningful constraint by mentioning 'private addresses refused' and 'bounded fetches,' but doesn't significantly expand on the schema's own description. Baseline 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?

States a specific action ('runs 12 agent-legibility checks'), a clear resource ('site URL'), and differentiates from the paid detail tool by framing the return value as 'enough to decide whether the paid per-check detail is worth it.' This distinguishes it from sibling site_audit tools effectively.

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?

Clearly signals this is a free, quick triage tool and hints at the paid per-check alternative for deeper detail. It doesn't explicitly name the sibling or state when NOT to use it, but the cost-decision context is strong and actionable.

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