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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered. The description adds genuinely useful behavior beyond that: it prefers the site's own llms.txt when one exists, otherwise synthesizes an index, and it caches for 24h with a rebuild escape hatch via `fresh`. What is missing is any sense of failure behavior for unreachable or non-indexable links.

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 short sentences, front-loaded with the purpose and return shape, followed by the fallback source and the caching caveat. No filler and nothing buried.

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 two-parameter read-only tool with no output schema, the description covers input scope, output structure, data source fallback and cache lifetime — everything needed to call it correctly. Only cross-tool routing is absent, which is scored under usage guidelines.

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 both parameters are already documented, including the optional scheme and the `fresh` cache-bypass. The description's "Cached 24h" reinforces the reason to use `fresh` but mostly restates what the schema says, so the baseline 3 applies.

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?

The description uses a specific verb ("Get an llms.txt index") and names the resource and even the return shape (title, one-line summary, sections of useful links). It is clear what the tool produces, though it never explicitly distinguishes itself from the sibling llms_full_txt, leaving the agent to infer the difference from names alone.

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?

Usage is implied rather than stated: the agent can infer this is the summarized-index variant and that it works on any public link, including PDFs and videos. There is no explicit when-to-use versus when-not guidance, and no route to llms_full_txt for agents that need full page text.

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