email_verify

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

Annotations already indicate readOnly, idempotent, open-world. The description adds valuable behavioral context: how role-address detection handles +tag stripping, how free_provider classification works for B2B signals, and the ethical reasoning for not including SMTP probing. No contradictions with annotations.

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 dense and front-loaded with the core function, then provides usage, exclusions, edge cases, and output details. While every sentence adds value, it could be slightly more concise without losing information.

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 is exceptionally complete given the tool's complexity. It covers purpose, when to use/not use, behavioral edge cases, rate limits, output structure, and ethical considerations. The output schema exists, so listing return fields in the description is a plus.

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 covers 100% of the single parameter, and the description adds meaningful details: examples ('admin@example.com'), requirement for '@', and context around usage. This fully compensates for the schema's minimal description.

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 identifies the tool as a one-call email validation service combining syntax, MX records, disposable check, role-address detection, and free-provider classification. It explicitly distinguishes from siblings like email_mx and email_disposable by stating it replaces 2-3 tool calls.

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 usage guidance: 'Use BEFORE adding an email to a contact list, sending an outbound message, or auditing a lead-list dump'. It also states what the tool deliberately does not do (SMTP probing) and suggests alternatives (Hunter.io/NeverBounce), plus mentions rate limits.

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