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

The description adds substantial behavior beyond the read-only/open-world annotations: it explains the returned verdict, deciding rule and line, crawl-delay, sitemaps, matching group lines, and tie-breaking logic. It also discloses important edge cases and pricing/error behavior, including no robots.txt allowing everything and server errors returning 503 without charge.

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 dense but front-loads the core purpose and then adds the necessary algorithmic and billing details. It could be more scannable, but almost every sentence carries relevant information.

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?

Given the output schema and annotations, the description is complete enough for correct invocation. It covers the core logic, edge cases, pricing, and error behavior without requiring the agent to infer critical details.

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 already 100%, so the schema documents both parameters well. The description still adds meaning by expanding the default user-agent set and clarifying that the URL identifies the page whose site's robots.txt is checked.

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 precise verb and resource: checking whether a URL path may be crawled under robots.txt per RFC 9309. It clearly distinguishes the tool from adjacent tools such as sitemap, llms_txt, and web_security_txt by focusing specifically on robots.txt crawl verdicts.

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?

The usage context is clear: use this to determine robots.txt crawl eligibility for a given URL and optional user agent. It does not explicitly name alternatives or exclusions, but the intended scenario is unambiguous.

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