Verify Email Address

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

Annotations already declare read-only, idempotent, non-destructive behavior. Description adds valuable context: it performs SMTP deliverability, DNS/MX validation, and various detections, and notes it is powered by WhoisXML API. This goes beyond annotations by detailing the verification techniques. However, it does not disclose rate limits or error scenarios.

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?

Two sentences: first lists core functionality with specific checks, second states result comprehensiveness and data source. Every word contributes to understanding. Front-loaded with purpose, no filler. Extremely efficient for the detail provided.

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?

Given the tool's complexity (multiple verification techniques), the description outlines key checks and references a known API provider. Output schema exists to cover return values, so missing return details are not a gap. Could mention possible failure reasons (e.g., email format invalid, API limit) but is largely sufficient for an agent to understand scope.

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?

Input schema covers the single parameter 'email' with 100% description coverage. The tool description does not add new parameter details beyond the schema's example. According to calibration, high schema coverage yields baseline 3, and description does not improve or worsen it.

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?

Description explicitly states 'Verify an email address' and lists specific checks: SMTP, DNS, disposable detection, catch-all, free provider, role account. Clearly distinguishes from a basic format validation tool by detailing the depth of verification. The verb 'verify' combined with the list of techniques provides unambiguous purpose.

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?

Description implies usage context (deep email verification) but does not explicitly state when to use this tool versus alternatives like 'email.validation.check' (a sibling tool). No guidance on when not to use or prerequisites. The presence of a similarly-named sibling without differentiation lowers the score.

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