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

Adds substantial behavior beyond annotations: 500 KiB size cap, 5 s timeout, redirect handling, RFC 9309 rules, exact verdict semantics including skipped cases, rate limits of 10/min and 30/hour per network, and a 10-minute cache. These details materially affect invocation and result interpretation.

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?

Dense but front-loaded: it starts with the core action and verdict, then adds limits, exclusions, rate limits, and caching. Every sentence contributes operational information without redundancy.

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?

Complete for this tool: output schema exists so return values need not be explained, and the description covers scope, constraints, failure modes, rate limits, and caching. An agent has enough information to invoke it correctly.

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%, so the URL parameter is already documented. The description nonetheless adds useful semantics: it must be a public http(s) URL, the check applies to the URL's site, and IP addresses and ports are not allowed.

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: fetch robots.txt for the given URL's site and report whether PriceMovedBot may fetch that URL. It clearly distinguishes the operation from fetching the page itself and names the exact verdicts returned.

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?

Provides clear context for when the tool applies, including the exclusions that it checks robots.txt rather than the page and only accepts domain names, not IPs or ports. It does not name explicit alternative tools, but none of the listed siblings compete with this purpose.

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