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

With no annotations provided, the description carries the burden of behavioral disclosure. It explicitly notes the cost model ('$0.01 via x402'), indicates it is a read operation, and mentions that the upstream is free (Wikimedia). It does not fully describe response shape or error behavior, but it gives a reasonable transparency profile for a simple lookup 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?

The description is compact and front-loads the most important details: cost, tool behavior, and outputs. 'Free upstream (Wikimedia)' and 'cheap fact-grounding' are slightly redundant with the cost mention, but the overall structure is clear and efficient.

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 read-only lookup tool with no output schema, the description covers purpose, cost, expected outputs, and ideal use case. It lacks explicit return-format and edge-case details, but an agent has enough context to invoke it correctly. Given the tool's low complexity, this is nearly complete.

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 already describes 'q' and 'limit' with 67% coverage. The description adds value by explaining the 'x_payment' mechanism ('$0.01 via x402') and clarifying that the query accepts 'any topic'. This partially compensates for the unexplained x_payment parameter and is consistent with 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?

The description clearly states a specific verb ('lookup'), a specific resource ('Wikipedia'), and concrete outputs ('article titles, extract snippets and canonical URLs'). It distinguishes itself from general-purpose siblings like web_search and tavily_search by focusing on Wikipedia as the knowledge source.

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 gives a clear use case: fact-grounding for read agents to reduce hallucination. This implies when to use it and what kind of task it serves, though it does not explicitly name alternatives or exclusion conditions. The context is clear enough for an agent to route appropriately.

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