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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real value by defining the status vocabulary (working, slow, down) and noting it is 'live', implying freshness, but says nothing about caching, refresh frequency, or auth needs.

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, front-loaded with the core purpose and followed by the field glossary. Slight redundancy: the return-value taxonomy (main_sites, file_hosts, free) is partly restated by an existing output schema, though it aids interpretation.

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 parameterless, read-only listing with an output schema and safety annotations, the description covers purpose and key field semantics, which is enough to invoke it correctly. Only the when-to-use framing is missing, a minor gap at this complexity.

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?

The tool takes zero parameters, so the baseline of 4 applies. The description introduces no parameter concepts to misunderstand, and the schema correctly documents an empty object.

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?

Specific verb ('List') plus resource ('the sites FetchPan can download from') with an explicit scope qualifier: live status. The catalog-listing intent is unmistakable against action siblings like download, check_link, and get_download_link.

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: an agent infers this is the discovery tool to consult before calling download or check_link, but the description never says when to call it or what to do with the result. No exclusions or alternatives are named.

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