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

Annotations cover safety (readOnly, idempotent, openWorld), but the description goes well beyond them: it discloses the exact price (0.01 USDC per completed call), the payment mechanism (x402 automatic payment when supported), and the failure policy (never charged if the call fails). It also reveals the shape of the output, including that each robots.txt decision comes with the rule that caused it and that a list of fixes is returned.

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 core capability is front-loaded in the first sentence, followed by two short, high-value sentences on cost and failure handling. The enumeration is long but each item is doing real work by telling the agent what the report will contain.

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 carries the burden of describing returns and does so thoroughly: crawler list, per-crawler deciding rule, meta robots, X-Robots-Tag, canonical, sitemaps with entry counts and freshness, llms.txt, and fixes. The billing and failure semantics close the remaining gaps for a paid, single-URL tool.

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?

There is a single parameter with 100% schema description coverage ('Public http(s) URL of the page or website'), so the schema already carries the semantics and the baseline is 3. The description adds no further detail such as whether a root URL is preferred over a deep page URL, but it also leaves no ambiguity.

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 precise verb+resource: check whether crawlers may read a page, and enumerates exactly what is inspected (robots.txt with Google matching rules and the deciding rule, meta robots, X-Robots-Tag, canonical, sitemaps, llms.txt, fixes). This is specific enough to separate it from check_structured_data, check_tracking and audit_landing_page even without naming them.

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 enumerated coverage implies when the tool is relevant (crawlability/indexability questions), but there is no explicit when-to-use, when-not-to-use, or routing to siblings such as full_site_report or audit_landing_page. Usage is inferable from the purpose statement rather than stated.

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