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

Annotations already mark the tool as read-only and open-world, so the safety profile is covered. The description adds the 'found on the web' context, but provides no detail on result sources, pagination, or limitations. 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, front-loaded sentence with no redundancy. It communicates the essential purpose in minimal words, which is ideal for an agent scanning tool descriptions.

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 simple one-parameter, read-only lookup with an output schema and annotations, the description is largely sufficient for calling the tool correctly. The main missing element is usage guidance relative to siblings, which affects selection but not invocation.

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 single required parameter `email` is self-evident from the tool name and description, and the schema provides format and pattern constraints. However, the description adds no additional semantic detail about the parameter beyond naming it, and schema description coverage is 0%.

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 and resource: find where an email address was found on the web. This clearly conveys the core function, though it does not explicitly differentiate it from sibling tools like email_finder or email_enrichment.

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?

No guidance is provided about when to use this tool versus siblings such as email_finder, email_enrichment, or domain_search. The description only states what it does, not when it should be chosen or excluded.

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