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

With no annotations, the description carries the full burden and does disclose the key behavioral trait: cost of 0.002 USDC per call via x402, plus exactly what payload comes back (lead summary, description, thumbnail, URL). It stops short of stating what happens when no article matches or whether the search is a fuzzy title match versus full-text — gaps that matter for a zero-annotation tool.

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 sentences, zero filler, and the return payload is front-loaded ahead of the pricing note. Every clause earns its place.

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 the returned fields, and the payment mechanics are fully covered by the schema's paymentProof text. The only meaningful omission is the no-match behavior, which an agent would want before committing a paid call.

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%, and the paymentProof parameter already documents the full 402 pay-and-retry flow, so the schema does the heavy lifting. The description only adds that the lookup spans 'any language edition,' which weakly supports the lang parameter but gives no format guidance beyond the schema's 'default en'.

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 ('Returns') and resource ('the lead summary, description, thumbnail and URL of the best-matching Wikipedia article'), including the fuzzy-match scope across all language editions. No sibling tool (web_extract, ai_answer, github_repo) overlaps with this Wikipedia-specific lookup, so an agent can select it unambiguously.

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: an agent can infer this is for looking up a topic or article title, but there is no explicit 'use this when…' statement or routing against alternatives like web_extract or ai_answer. No exclusions or prerequisites are given beyond the payment note.

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