verify_email

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

With no annotations, the description is the only source of behavioral information. It does disclose that MX checking is 'live' and lists concrete verifications (syntax, disposable domains, reputation), implying network dependency. However, it omits potential side effects such as latency, whether any email is sent, or failure/timeout 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 a single, information-dense sentence that front-loads the tool's purpose and then lists differentiating capabilities. Every phrase carries weight, with no filler or redundant restatement of the tool name.

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?

The description covers the main verification steps but, since there is no output schema, it does not explain what the tool returns (e.g., a boolean, a score, or a structured report). It also lacks guidance on error handling, timeout behavior, or the impact of the live DNS lookup, leaving meaningful gaps for an agent consuming the result.

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%: both 'email' and 'check_mx' have meaningful descriptions. The tool description reiterates the live MX check but adds no additional parameter-level semantics, such as accepted email formats or how check_mx affects the overall verification flow.

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 opens with 'B2B email and deliverability verifier' and enumerates specific functions: RFC 5322 syntax validation, live DNS MX verification, disposable domain detection, and reputation scoring. This clearly differentiates verify_email from its siblings (e.g., lookup_ip, repair_json), which address unrelated concerns.

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 gives a clear context for when to invoke the tool: verifying B2B email addresses and assessing deliverability. However, it does not explicitly state when not to use it or mention alternative tools, though the sibling list contains no competing email tools.

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