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

Annotations already cover readOnly, idempotent, openWorld and non-destructive behavior, so the bar is lower. The description adds genuinely new context that annotations cannot express: the x402 payment model, the $0.08 USDC on Base price, and the X-PAYMENT header requirement. It could go further on what happens when payment is missing or rejected, but the auth/cost disclosure is valuable.

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 short sentences, front-loaded with capability and cost, and no filler. Every clause carries information the agent needs to decide and pay.

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?

This is a paid, multi-parameter tool with no output schema and zero schema descriptions, so the description bears a heavy load. It covers the payment mechanics well but leaves num undefined and says nothing about the shape of the batch response or per-query failure behavior.

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 must carry parameter meaning. It maps loosely onto queries via "up to 25," but the num parameter (1-20) is never explained at all — an agent cannot tell whether it is results-per-query, concurrency, or something else. With two undocumented parameters, this is a real gap.

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?

"Up to 25 Web searches in one call" gives a specific verb (searches) and resource (web) with a batch scope, which distinguishes it from the single-query web_search sibling. It stops short of an explicit sibling comparison, but an agent can infer the batch role from the 25-query cap.

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 rather than stated: "in one call" and the 25-query cap signal batch scenarios, but it never says when to prefer batch_search over web_search or how to split work between them. It also omits what to do if a payment cannot be supplied.

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