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

With no annotations, the description carries the full burden and does so well: it discloses that JavaScript is not rendered, an overall 10-second budget, a 2 MB HTML cap, a maximum of 20 links, and that only ports 80/443 on public HTTP/HTTPS are reachable. These are exactly the hard limits that determine whether a call can succeed, plus the shape of the response.

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?

Highly front-loaded: the capability is stated first, then return shape, then hard limits, all in four dense sentences with no filler. The trailing '(API Tool Calls, by Cowerx)' attribution adds no decision-relevant information, which is the only wasted text.

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?

For a single-parameter tool with no output schema, the description covers everything needed: what it does, what it returns, and the operational limits that govern success. Return values are enumerated in the description, compensating for the absent output schema.

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% for the single url parameter, so the baseline is 3, but the description adds real constraint meaning beyond the schema: the page must be public and served on HTTP/HTTPS ports 80/443 only. That materially narrows what values will work.

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 one public HTML page') with the scope qualifier 'with fixed SEO rules', and the return payload (schema 1, score, strengths, ranked fixes, facts) makes clear this is an SEO audit rather than a markdown conversion (page_to_markdown) or text review (proofread). An agent can distinguish it from every sibling without opening a schema.

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?

Usage is implied by the constraints ('one public HTML page', public ports only), so an agent can infer the tool is for auditing a single reachable page. However, it never names an alternative or states when-not to use it (e.g., versus page_to_markdown for content extraction), leaving the routing decision to inference.

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