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

Annotations already declare read-only/non-destructive behavior, and the description adds substantial detail: sitemap-first discovery with homepage crawl fallback, a sampled subset, summary-only output without finding text or page locations, and the paid full-report tier. This gives an agent realistic expectations about result granularity and limitations.

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?

Four sentences, each carrying distinct value: method, return shape, invocation timing, and report limitation/upsell. The description is front-loaded and free of filler, though the final commercial sentence is slightly promotional.

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 one parameter and no output schema, the description adequately explains what is returned (counts, severity counts, categories), what is not returned, and the fallback crawling behavior. Minor ambiguity remains around the exact sample size, but the description is sufficient for correct invocation.

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?

The single 'site' parameter is fully documented in the schema with 'example.com' as an address example. The description reinforces 'website address' but adds little format-level detail beyond the schema, so the 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?

The description states a specific action: discover pages from a sitemap or crawl, then check a sample for WCAG 2.1 accessibility and prompt-injection issues. The 'site-wide' framing and 'single-page scan would miss' contrast clearly distinguish it from sibling page-level tools like accessproof and cloakcheck.

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 explicitly says to call this 'before launch or handoff' and explains that it catches site-wide issues a single-page scan would miss. It could be stronger by naming exact alternative tools for single-page checks, but the timing and scope guidance is clear enough.

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