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

The readOnlyHint and openWorldHint annotations already cover the safety profile and data availability. The description adds 'when available' and clarifies returns include direct and company numbers, but it doesn't disclose asynchronous behavior when webhook_url is provided. There is no contradiction with 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 a single, focused sentence with an active verb and no filler. It front-loads the purpose and adds relevant output context efficiently.

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 zero required parameters in the schema, the description should explicitly state that at least one of email, domain, or linkedin must be provided. It also omits that webhook_url changes delivery to asynchronous. These operational gaps prevent full completeness, though the output schema and annotations cover much of the rest.

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 each parameter is already documented. The description only restates the lookup categories in prose and doesn't clarify interactions between parameters, mutual exclusivity, or the effect of full or webhook_url.

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 identifies the tool's purpose: finding phone numbers via email, domain, or LinkedIn profile. It also specifies what kind of results are returned (direct and company numbers). It doesn't distinguish itself from siblings like mpp_phone_finder or phone_validator, which prevents a top score.

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 when to use the tool: when an agent has an email, domain, or LinkedIn profile and needs associated phone numbers. However, it doesn't explicitly say when not to use it, nor does it mention alternatives such as phone_validator for verification tasks.

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