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

Annotations already declare the operation read-only, idempotent, and non-destructive. The description adds genuinely useful behavioral context beyond that: it names the exact REST endpoint (wikipedia.org/api/rest_v1), states that no auth is required, and clarifies the default-language behavior. It does not discuss edge cases such as missing or disambiguated titles, but the annotations and output schema reduce the severity of that omission.

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?

Three short sentences with no filler. The core verb, target resource, fields returned, language behavior, endpoint, and auth status are all included efficiently, with the most decision-relevant information front-loaded.

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 two-parameter, read-only tool with an output schema and strong annotations, the description covers the essential invocation requirements: title, language selection, API source, and auth. It would be slightly more complete if it addressed the redundant-looking wikipedia.article.summary sibling and error behavior for unknown titles, but nothing critical is missing for calling it correctly.

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 description coverage is 100%, so the schema itself already documents title format and lang defaults/examples. The description mostly repeats the lang default and examples rather than adding new semantic detail, which corresponds to the baseline-3 case where the schema does the heavy lifting.

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 names a concrete verb-resource pair ('Get ... for a Wikipedia article by title') and enumerates the returned data: intro extract, short description, thumbnail, and canonical article URL. It is clear and specific, but it does not explicitly differentiate itself from the near-duplicate sibling wikipedia.article.summary, so it stops short of a 5.

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 context is present in implied form: use this tool when you need a Wikipedia article summary, with lang as the edition selector and the backing API/auth posture supplied. However, it gives no explicit guidance on when to prefer this over the similar sibling wikipedia.article.summary, nor does it list exclusions or alternative tools for media/search use cases.

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