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

Annotations already declare readOnlyHint and destructiveHint=false, yet the description adds real context: only REST-enabled taxonomies are returned (so absence is meaningful), and it explains the semantic of the `hierarchical` flag and the `types` field. The "runs straight away" note mildly restates the read-only annotation but usefully signals no approval step.

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?

Front-loaded with the definition and return shape, followed by the one non-obvious semantic (`hierarchical`) and a practical tip. Most sentences earn their place, though the trailing Royally/read-only sentence duplicates what annotations already assert.

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?

No output schema exists, and the description compensates by describing the returned object's fields (slug, name, description, rest_base, types, hierarchical). For a zero-required-param read tool that is essentially complete; only field-level detail for edge cases is absent.

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 (site_id) and schema description coverage is 100%, with an enum and a human-readable site host, so the schema carries the load. The description never mentions site selection, which is fine given the coverage — baseline 3 per rubric.

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?

States a specific verb and resource ("Lists all registered WordPress taxonomies") plus scoping qualifiers (built-in and plugin-added, REST-enabled only) that separate it from term-level siblings like wp_list_terms or wp_get_categories. The enumerated return fields make it unambiguous that this returns taxonomy *definitions*, not terms.

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 only implied: the agent can infer it should call this to discover taxonomies before filtering terms, and it gets a downstream tip ("Use rest_base when calling REST taxonomy endpoints directly"). There is no explicit when-to-use/when-not or named alternative such as wp_list_terms or wp_get_post_types.

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