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

Annotations already declare readOnlyHint and openWorldHint. The description adds valuable context beyond that: exact price ($0.50 USDC), payment mechanism (x402 on Base), and failure policy ('not charged if the call fails'). It also confirms the tier limits (5 prompts, 1 engine).

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?

A single compact sentence with two clauses, front-loaded with purpose and followed by cost/payment details. Every clause carries essential information; no waste.

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 definition covers purpose, cost, payment, failure policy, and tier limits, and the rich schema describes all 7 parameters. It lacks any description of the return value, but with no output schema and annotations covering read-only/open-world behavior, this is a minor gap for selection purposes.

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 coverage is 100%, so the baseline is 3. The description adds meaning by specifying the quick tier's caps: 5 prompts and 1 engine, which clarifies the promptCount and engines parameters beyond the schema's generic 'capped by the tier' and 'subset of engines'.

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 states a specific resource (AI brand visibility) and scope (quick check, 5 prompts, 1 engine). It implicitly distinguishes from the deeper sibling tools via 'quick check', though it does not name them explicitly.

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 phrase 'quick check' implies a use case for fast, low-cost sampling, but there is no explicit guidance on when to choose this over ai_visibility or ai_visibility_deep, nor any when-not conditions.

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