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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so safety is covered. The description adds genuine value beyond that by disclosing that the result set is partial (saved wp_navigation posts only), but it says nothing about ordering, pagination, or whether non-published navigation entities are included.

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 short sentences with zero filler; the positive statement of purpose comes first and the scope exclusion follows. Every sentence carries distinct information.

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 single-parameter, read-only list tool with full annotation and schema coverage and no output schema, the description covers purpose and the key scope caveat. Only the routing relationship to the similar wp_list_menus tool is left unaddressed.

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?

There is a single parameter at 100% schema coverage, and the schema already instructs the agent to call list_sites first and not to pass a URL or post ID. The description adds no further meaning about site_id, which is acceptable given the schema fully documents it (baseline 3).

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+resource pair, 'Lists saved wp_navigation posts', and sharply limits scope with 'Does not discover navigation built directly in templates or template parts'. It does not explicitly distinguish itself from the sibling wp_list_menus, so an agent must still infer how the two differ.

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?

There is a clear negative guideline — this tool will not surface template-embedded navigation — which implicitly tells the agent when this tool is insufficient. However, no positive guidance is given about when to prefer this over the closely named wp_list_menus sibling, leaving the main routing decision to inference.

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