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

Annotations already cover readOnly, idempotent, non-destructive and open-world, and the description adds meaningful method: it fetches robots.txt per bot, makes live requests with each bot's User-Agent to surface CDN/firewall blocks, checks noindex, and inspects raw HTML without JavaScript. That tells the agent this involves real outbound requests per bot and what failure modes it can detect, well beyond what the annotations convey.

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?

Front-loaded with the core question and then the evidence gathered, with the usage examples last where they belong. Sentences are dense but every clause carries information; the only mild cost is length in the enumeration of checks.

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?

For a single-input diagnostic tool with no output schema, the description supplies the return shape itself (a score, per-bot access, copy-ready fixes) plus the scope limits implied by the schema. An agent has everything needed to call it and interpret the result.

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 exists and the schema documents it at 100% coverage, including accepting a bare domain and refusing private/local addresses. The description adds no further detail on accepted URL forms or normalization, so it sits at the baseline where the schema does the work.

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 (check) and a precisely scoped resource: whether named AI assistants and crawlers can reach, read and cite a URL. The enumeration of the checks performed (robots.txt, User-Agent requests, noindex, no-JS text) makes it unmistakably distinct from generic siblings like check_url or check_link_preview, 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?

Gives explicit intent triggers with quoted example questions ('can ChatGPT see my site', 'why doesn't Perplexity cite my page'), which is strong when-to-use guidance. It stops short of stating when not to use it or naming an alternative tool for adjacent cases (e.g. plain reachability or performance).

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