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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so safety is covered. The description adds useful behavioral context about the payload (per-directory item counts, dates, and links), which matters because there is no output schema, though it says nothing about ordering, pagination, or freshness semantics.

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?

It is a single front-loaded sentence that states what is returned and what fields accompany each entry. The long parenthetical list of directories is dense but arguably earns its place as the tool's actual output vocabulary; structure could be improved by separating inputs from output fields.

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?

With no parameters, no output schema, and full annotation coverage, the description carries the remaining burden of explaining the return payload, and it does so (directory names, item counts, dates, links). An agent has enough to call it correctly; only relative positioning against analogous siblings is missing.

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 is 4. There is nothing for the description to disambiguate about inputs, and it correctly does not invent any.

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 clearly states the resource (site directories) and enumerates the specific directory categories, so an agent knows exactly what data is returned. It does not explicitly distinguish itself from the nearby sibling site_sections, leaving a small ambiguity about which to pick for a general site map.

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 by the enumeration of directory types (discovering what catalogs exist), but there is no explicit when-to-use or when-not-to-use guidance. The presence of site_sections and search_site among siblings makes a routing hint valuable, and none is given.

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