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

The description explicitly discloses a side effect (verification credit consumption) and the asynchronous behavior (returns 'pending' after >10s, call again to poll). With no annotations provided, this is valuable transparency beyond the bare action.

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 compact and front-loaded: the core purpose appears first, followed by a concise note about credit and polling. Every sentence adds necessary operational information without redundancy.

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 one-parameter tool with no output schema and no annotations, the description covers purpose, side effects, and polling behavior. It omits details like the exact response format or how to identify the stored result when polling, but the low complexity keeps this from being a major gap.

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 schema has 0% description coverage, so the description needed to clarify the email parameter. It only adds 'single email address,' which conveys singular use but provides no format, validation rules, or constraints beyond the parameter name itself.

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 uses a specific verb ('Verify') with a clear resource ('a single email address') and defines the result categories ('valid / invalid / catch-all'). This clearly differentiates the tool from siblings like search_leads_by_email or get_email, which serve different purposes.

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 given about when to use this tool versus alternatives. There is no mention of when to prefer verify_email over search_leads_by_email, get_email, or list_emails, nor any exclusion criteria or prerequisites.

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