Verify a single email address

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

With no annotations, the description carries the full burden. It discloses the deliverability verdict, reason, flags (disposable, role account, catch-all, etc.), recommendation, and credit usage—giving a solid picture of behavior. It does not mention error handling or rate limits, but for a verification tool, it transparently indicates output and cost.

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 sentence, front-loaded with the core purpose ('Verify one email address in real time'), followed by a concise list of valuable outputs. Every clause adds meaningful detail without redundancy or fluff.

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 one parameter, no annotations, and no output schema, the description covers the purpose, the return values (verdict, flags, recommendation), and the cost (credit usage). It could add error handling or timeout behavior, but for a straightforward verification tool, it is largely complete.

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 coverage is 100% and the only parameter 'email' is described with an example ('e.g. lead@example.com'). The description adds no extra parameter semantics, but the parameter is self-explanatory, so the baseline score of 3 is appropriate.

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: 'Verify one email address in real time.' It clearly distinguishes itself from batch and list-cleaning tools by emphasizing the singular, real-time nature. It also enumerates key outputs (verdict, flags, recommendation, credit usage), making the tool's purpose unambiguous.

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 phrase 'one email address' and 'real time' implies this is for immediate single-address checks, which implicitly contrasts with batch tools like verify_batch. However, it does not explicitly name alternatives or state when not to use this tool, so it provides clear context but lacks explicit exclusions.

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