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

Annotations already cover read-only and open-world behavior, but the description adds real value beyond them: it names the nine specific user agents, discloses that evaluation is done 'the way crawlers do', and explicitly limits scope to robots.txt (excluding CDN/firewall rules) — an important non-obvious caveat that prevents false-negative conclusions.

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, zero filler. The core behavior and the crawler list are front-loaded, and the scope limitation is stated last as a short caveat.

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?

Output schema exists, so return values need not be re-explained, yet the description still summarizes the result shape. Combined with the crawler enumeration and the CDN/firewall caveat, an agent has everything needed to call it correctly and interpret the answer.

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?

With one parameter at 100% schema coverage, the schema already documents the url field including format and an example. The description adds only the qualifier that the target must be a 'public' page, which is marginal beyond structured data. 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 and resource ('reads a site's robots.txt') plus the exact crawler set it emulates (Googlebot through Perplexity-User) and the return shape (which may fetch, which rule blocks). This is clearly distinguishable from siblings like check_page_readability or check_page_visibility.

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 name and description — checking whether named AI crawlers can fetch a URL — but it never states when to prefer this over check_page_visibility, check_store_ai_readiness, or lookup_index_score. The one explicit boundary ('Does not see CDN or firewall rules') is a scope exclusion rather than an alternative-selection rule.

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