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

Annotations already declare readOnlyHint and non-destructive behavior. The description adds meaningful behavioral context beyond that: the honesty check that flags third-party/placeholder addresses rather than presenting them as the company's own, plus pricing details. This provides transparency into how the tool handles potentially misleading data.

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 a single, well-structured sentence that front-loads the core function ('Extract public contacts...') and appends the differentiator and pricing in a logical dash-separated clause. No wasted words—every element earns its place.

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?

With 4 parameters and no output schema, the description covers the essential purpose and a key behavioral trait (honesty check). It does not explicitly describe the output structure, but the phrase 'flags third-party/placeholder addresses' implies output includes contact entries with flags. Given the rich schema descriptions, the description is sufficiently complete for practical use, though it could mention return format or limits.

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?

The input schema has 100% parameter description coverage, thoroughly explaining domains, checkPages, maxConcurrency, and maxPagesPerDomain. The tool description itself adds no parameter-specific semantics; it only restates the overall purpose. Since the schema carries the burden, the baseline of 3 applies.

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 verb ('Extract') and resource ('public contacts a company posted on its own site: email, phone, social links'). It also conveys a key differentiator (the honesty check) that separates it from sibling tools like email-verifier or company-lookup.

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 implies a use case (finding contacts a company publicly posted on its own site) but does not explicitly explain when to prefer this tool over alternatives, nor does it state exclusions. There is context but no direct alternative comparison or when-not-to-use guidance.

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