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

Annotations already cover safety (readOnlyHint, destructiveHint=false, idempotentHint, openWorldHint), so the lower bar applies. The description still adds real value by disclosing that it performs live server requests in addition to reading robots.txt, and by explaining the dual result shape (robots.txt verdict vs. server response) even though no output schema exists.

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 sentences, no filler, with the primary action front-loaded and the payoff ('who is blocked and by what') closing it. The crawler list is dense but each name earns its place by defining scope.

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 no output schema, the description does the necessary work of explaining the return shape and what is compared. Minor unresolved gaps remain — behavior when robots.txt is absent, and any latency or rate-limit expectation for the live server tests — but nothing that would cause a misinformed call.

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?

Only one parameter and schema description coverage is 100%, with the schema already giving a format example ('example.com'). The description contributes nothing about the site argument itself, so the baseline 3 applies; an explicit note on whether schemes/paths are accepted would have raised it.

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?

Names a specific verb and resource ('Read a site's robots.txt and test the server') and enumerates exactly which eight crawlers are probed. The stated output ('per crawler, whether robots.txt allows it and whether the server answers it') makes the tool's contract unmistakable and clearly distinct from a generic page check.

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 outcome clause 'so you can see who is blocked and by what' implies the diagnostic use case, but there is no explicit when-to-use, no exclusions, and no reference to the closely related sibling check_llms_txt, which an agent could easily confuse with this tool for AI-crawler questions.

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