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

Annotations already declare readOnlyHint=true and openWorldHint=true, and the description usefully adds the beyond-annotation behavior: missing inputs are backfilled from the homepage and sitemap.xml (explaining the open-world access), and the response is file text plus improvement notes. It stops short of noting fetch limits, failures, or cost.

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?

Three tight sentences with no filler: what it makes, how inputs are resolved, and what comes back. The most decision-relevant information (the artifact) is front-loaded.

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 read-only generator with no output schema, the description covers the return payload and the input-resolution behavior, which is the critical missing piece. The remaining gap is minor: max_pages and site_name semantics, and any distinction from the robots.txt sibling.

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 description coverage is 60% (pages, summary, site_url documented; site_name and max_pages bare), so the baseline is 3. The description reinforces the fallback semantics for pages/summary and names site_name, but it never explains max_pages or its 5–60 bounds, leaving one parameter undocumented in both places.

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 artifact ('Generate an llms.txt file') plus the governing format (llmstxt.org) and the target ('a public website'), so the agent knows exactly what is produced. It does not, however, distinguish itself from the sibling generate_ai_robots_txt, which is the nearest-neighbor alternative.

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?

Scoping is implied by 'for a public website' and the fallback rules tell the agent it can call with just site_url, but there is no explicit when-to-use/when-not guidance and no routing to or away from generate_ai_robots_txt.

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