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

Annotations already cover safety (readOnly, idempotent, openWorld, non-destructive), so the bar is lower, and the description adds real context beyond them: it is a public REST call and consumes 1 unit of monthly quota per invocation, which is a material operational constraint. It stops short of describing failure modes (missing article, unsupported language) or throttling.

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?

Two compact sentences with the core capability front-loaded, followed by the cost note. The internal operation identifier ('wikipedia-article.get') is arguably noise for an agent, but there is no wasted prose.

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 usefully enumerates the returned fields, and the schema plus annotations cover inputs and safety. The only gap is the absence of guidance on error/empty-result behavior for a two-param lookup tool, which is minor given the low complexity.

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 both parameters are already documented in the schema, and the baseline is 3. The description adds only a light hint that language is constrained to 'supported' languages, but contributes no syntax or format detail beyond what the schema supplies.

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 ('Fetch') and resource ('Wikipedia article summary') and enumerates exactly what the response contains (description + extract + thumbnail + coordinates), which no structured field provides. This is clearly distinguishable from siblings like github_repo_get or web_search_post, which target different resources.

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 by the tool's obvious subject matter (retrieve a Wikipedia summary), and the quota cost note gives a decision cue for high-volume callers. However, it never states when to prefer this over alternatives such as web_search_post for factual lookups, nor any exclusions.

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