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

With readOnly, openWorld, and idempotent annotations already covering safety and side effects, the description adds valuable behavioral context: the HEAD-probed nature of the llms-full.txt check, the fact that every attempted rung is returned, and that misses are diagnosable. This goes well beyond what annotations alone communicate.

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?

Two sentences with no filler. The core behavior and output contents are front-loaded, and the usage guidance follows naturally. Every clause earns its place, and the structure gives the agent the key decision information early.

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?

Despite lacking an output schema, the description conveys what will be returned (title, summary, H2 links, Optional section, llms-full.txt indicator) and how failures behave ('every rung tried is returned so a miss is diagnosable'). Combined with the annotations and the sibling-routing guidance, an agent has enough context 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 description coverage is 100%, so the schema already documents all three parameters. The description reinforces the URL-centric purpose and mentions the parsed output, but it does not add meaningful detail about the parameters themselves beyond what the schema provides. Baseline 3 is appropriate.

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 ('Find and parse') with a clear resource ('the llms.txt that covers a site or page URL') and enumerates the exact parsed contents (title, summary, H2 sections, Optional section, llms-full.txt existence). It also differentiates from the sibling llms_page by saying 'Use first, before llms_page,' so an agent can distinguish it without opening the schema.

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 description explicitly states when to use this tool: 'Use first, before llms_page, whenever the user needs a product or library's own docs.' This provides clear routing relative to llms_page. It does not explicitly mention when llms_search would be preferable, so the guidance is strong but not fully exhaustive.

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