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

Annotations already declare readOnlyHint=true and openWorldHint=true, and the description reinforces this by stating 'without saving anything' and 'Free — searching never spends credits; only revealing contact details is metered.' This adds valuable behavioral context about credit usage and side-effect-free operation beyond the annotations.

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-loaded with the core purpose, then adds the credit/read-only context and usage guidance. The read-only key sentence is slightly tangential to the tool's core function but still useful for access decisions.

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 read-only counting tool with no output schema, the description covers purpose, cost behavior, and usage context. It doesn't describe the return format (e.g., whether it returns a single number or a breakdown), but the tool's simplicity and the annotations reduce the need for that detail.

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%, so the schema already documents all six parameters with examples. The description adds the overall semantic that these are ad-hoc targeting criteria, but doesn't add per-parameter meaning beyond what the schema provides. Baseline 3 is appropriate.

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 the tool counts matching prospects for ad-hoc targeting criteria without saving anything, distinguishing it from lead sourcing and ICP creation tools. It names the specific resource (audience size) and the verb (counts), making the purpose unmistakable.

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 explicitly says to use it to validate targeting before creating an ICP or sourcing leads, and clarifies when not to use it (not for revealing contact details). It also notes that a read-only key may call it, which is a clear access guideline.

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