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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, so the bar is lower; the description adds genuinely new operational context — 300+ language editions, official Wikimedia REST endpoints, CC BY-SA attribution, and x402 pay-per-call settlement in USDC on Base. The payment precondition is the most valuable disclosure since it gates invocation. It does not mention rate limits or truncation behavior.

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 core value proposition and output contents, followed by provenance and payment mechanics. Three sentences, each carrying information; the 'cheapest way' phrasing is a mild sales claim but still signals cost relevance.

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 compensates by enumerating return fields (extract, short description, canonical URL, thumbnail) and disclosing the paid-call flow that governs how the tool is actually invoked. A grounding tool of this complexity is adequately covered, though error/empty-match behavior is unstated.

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 all four parameters (query, lang, limit, _payment) are already documented in the schema; baseline is 3. The description reinforces the language breadth (300+ editions) and the payment flow for _payment but adds no format or range detail beyond 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?

States a specific verb+resource: 'Wikipedia search plus the full summary of the best match', and enumerates the payload (extract, short description, URL, thumbnail). It is clearly distinct from generic siblings, though it never explicitly names web_search or paper_search as the alternatives it differs from.

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?

Gives a clear usage context with 'ground an entity before reasoning about it' and positions itself as the cheapest grounding path, which tells the agent when this beats broader tools. It stops short of explicit when-not conditions or naming a sibling alternative, so it is not a 5.

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