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

Annotations already declare readOnly, openWorld, idempotent and non-destructive, so the description is not obligated to restate safety. It adds genuinely new behavioral context the annotations do not carry: a per-call cost of $0.02 USDC on base and the requirement to pass an x402 payment in the X-PAYMENT header, which prevents a failed call. It does not state what happens on missing or invalid payment.

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 dense sentences with no filler, and the payload description is front-loaded ahead of the payment mechanics. It is appropriately sized for the tool, though the parenthetical cost notation is slightly compressed.

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?

The description does sketch the return shape ('clean markdown of the top N results') in lieu of an output schema and explains the payment flow, which covers the big unknowns. However, with four parameters at 0% schema coverage and a duplicated q/query pair, the definition does not give an agent enough to construct a correct call without trial and error.

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 0%, so the description carries the full burden, and it only clarifies that N is bounded 1-5. It says nothing about how q differs from query (both string params, no required fields) or what maxChars controls, leaving an agent guessing about the most error-prone part of the call.

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 specific verb-plus-resource: web search combined with returning clean markdown of the top N results. That composite scope implicitly separates it from the plain web_search and extract siblings, though it never names them explicitly, so an agent must infer the distinction.

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: the mention of a $0.02 USDC x402 charge signals this is the paid, combined alternative to free siblings like web_search or extract. There is no explicit when-to-use, when-not-to-use, or named alternative anywhere in the text.

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