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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered by structured data. The description adds the return shape (area names plus active widget IDs) in the absence of an output schema, which is useful context, but says nothing about ordering, pagination, or whether inactive widgets are excluded.

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?

One front-loaded sentence that states the resource and the returned fields with zero filler. Nothing is redundant or 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 simple, annotation-covered read tool with one fully documented parameter, this is nearly sufficient: the agent knows what it returns and how to supply site_id. A brief note on how the returned IDs relate to the widget CRUD siblings would close the remaining gap.

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 single parameter is fully documented in the schema at 100% coverage, including the crucial instruction to call list_sites first and not to pass a URL or post ID. The description adds no further meaning beyond that, so the baseline of 3 for high schema coverage 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 gives a specific verb ("Lists") and resource ("registered widget areas (sidebars)") plus what is returned ("active widget IDs"). It does not, however, distinguish this from nearby siblings such as wp_elementor_list_widgets or wp_read_widget, so the agent must infer the boundary 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?

There is no when-to-use or when-not-to-use guidance. Nothing tells the agent to call this before wp_create_widget/wp_move_widget to discover area IDs, or to use wp_read_widget when it needs the widget's content rather than its ID.

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