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

Annotations already mark readOnlyHint=true and destructiveHint=false; the description reinforces read-only and adds a unique cost signal ('FREE'). It goes beyond annotations by explaining the semantic distinction between declared vocabulary and used vocabulary and confirming that both are returned, which is a key behavioral nuance. No contradiction with annotations.

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?

The purpose is front-loaded in the first clause, followed by essential scope details and the cost/read-only note. The bracketed capability and mirror lines are compact and informative; no sentence feels wasted.

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 one-parameter, read-only tool with an output schema, the description covers what is returned and the semantic distinction that matters. It is missing only an explicit pointer that topic values come from list_topics, though the sibling tool and default value make this easily recoverable.

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 input schema only provides a 'topic' string with a default, and the description adds that the call addresses ONE topic while the mirrored endpoint (topics/:slug) implies the parameter is a topic slug. It does not enumerate valid values or point to list_topics for available slugs, so the low schema coverage is only partially compensated.

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 opening phrase 'Describe ONE topic in full' names a specific verb and resource, then enumerates the exact content returned: axes, operative definitions, controlled theme/quality vocabularies, and in-use vocabulary counts. The 'ONE' scope and the explicit vocabulary facts clearly distinguish it from a listing tool like list_topics.

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?

The description makes the read-only, single-topic use case clear, but it does not explicitly say when to prefer this over alternatives or when not to use it. No sibling routing is provided, so an agent must infer that list_topics is for enumeration. This is implied usage, not explicit guidance.

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