On-page SEO audit of a URL

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

Annotations already cover readOnly, openWorld, idempotent, and non-destructive behavior. The description adds that it fetches 'like a crawler' and that no authorization is needed, reinforcing the open-world and read-only traits. It doesn't mention rate limits or potential blocking, but the annotations lower the bar; the added context is useful.

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?

The description is a single long sentence that front-loads the action and then lists outputs in a clear sequence. It is efficient in packing a lot of information, though it is a run-on and could be broken into bullets. Still, it is concise relative to the breadth of content.

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 complex with no output schema, but the description enumerates the major output categories comprehensively (redirects, status, metadata, headings, link counts, schema types, etc.). It also states the input (any URL) and the access requirement (none). The only gap is parameter details, but those are partially in the schema. For a crawler-like tool, this is quite complete.

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 only 33% (only maxHeadings has a description). The tool description does not explain any parameter semantics, such as the effect of maxHeadings or maxImagesMissingAlt. With low schema coverage, the description should compensate, but it only lists outputs and ignores parameters entirely. An agent would need to rely on the schema alone, which is insufficient for maxImagesMissingAlt.

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?

The description clearly states the verb ('Fetch a page like a crawler and report') and the resource (a URL), and enumerates a comprehensive list of outputs (final URL, status, title, meta, robots, etc.). It distinguishes itself from siblings like robots_check or pagespeed by being a full on-page audit, so an agent can tell it apart without opening schemas.

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?

It states when to use it ('Works for any site, no authorization needed') and implies it is for a full audit, but it does not explicitly contrast with alternatives or give exclusions. For example, it doesn't say 'use robots_check if you only need robots'. The broad scope is implied, but not explicitly routed.

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