Emails Validator

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

No annotations are provided, so the description carries the full burden for behavioral disclosure. It mentions 'documented /email-validator endpoint' but does not describe key behaviors such as rate limits, whether validation includes deliverability vs. syntax, how invalid addresses are handled in responses, or the distinction between sync and async execution. The schema hints at async/webhook options, but the description adds no transparency about how these affect behavior.

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 concise: one opening sentence plus three bullet points, all directly relevant. It front-loads the primary action and use cases without any redundant filler. Every sentence 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?

For a tool with an output schema and fully documented parameters, the description covers purpose and usage context well. It lacks behavioral transparency (e.g., async behavior, return details), but the output schema and parameter descriptions fill many gaps. Overall it is nearly complete for an agent to decide when to invoke it.

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 parameters are fully documented in the schema (query array, async deprecated flag, webhook URI, execution_mode enum). The description adds no additional parameter semantics beyond what the schema already provides, earning the baseline score of 3.

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 'Validate email addresses' with a specific resource ('documented /email-validator endpoint'). The bullet list of best-for use cases further clarifies the tool's distinct function. It is unambiguously differentiated from the sibling tools, which are mostly search/enrichment or management tools, making this the only email validator.

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 provides explicit context on when to use the tool via the 'Best for' bullet points: deliverability checks, outbound lead list validation, and filtering invalid emails before enrichment/outreach. It does not name alternative tools or state when not to use it, but the use-case guidance is clear and actionable.

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