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

Goes well beyond the readOnlyHint annotation: it discloses that `area`, `search` and pagination are applied locally (i.e. not server-side filtering), that an active block theme with Full Site Editing is required, and what the response object contains. The only repetition is the read-only framing ('runs straight away'), which adds the useful 'no approval needed' nuance rather than merely restating the annotation.

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?

Single dense paragraph, front-loaded with the purpose, then parameters, then return shape, then prerequisites. Every clause carries information an agent would otherwise have to infer, and there is no filler.

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 output schema, the description supplies the return shape (field list plus total/total_pages/page/per_page) and the ID convention, and it flags the block-theme prerequisite. Combined with annotations covering safety, nothing material is missing for a correct call.

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 coverage is already 100%, so the baseline is 3; the description still adds value by explaining that template parts are 'the header, footer and other reusable areas', that `area` is an empty string for templates, that defaults/max apply to `per_page`, and that pagination/filtering happen locally. It does omit the `site_id` parameter, which is only explained in the schema.

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?

Opens with a specific verb + resource: 'Lists block templates or template parts', and immediately distinguishes the two modes it can return. An agent can tell this apart from the single-object sibling wp_get_template without reading either 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?

Usage is implied rather than stated: it notes that returned IDs 'are accepted by wp_get_template / wp_update_template with the same `type`', which hints at a list-then-fetch/update workflow. But it never says explicitly when to choose this over wp_get_template or the other template-related siblings, and gives no exclusions.

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