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

With no annotations provided, the description carries the burden of behavioral disclosure. It discloses that the address is disposable, that the tool does not send the test email itself (the USER must send it), that it is free, and that results arrive via a separate follow-up call. It stops short of mentioning expiration or rate limits, but the core behavior is clear.

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 primary action appears first, followed by a dense audit checklist, a required user action, and a pointer to the result tool. Every sentence earns its place, and 'Free tool by Postbox Services' is a useful cost signal rather than filler.

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 zero-parameter tool with no output schema, the description covers the essential workflow, the audit dimensions, and the follow-up call. It could be slightly more explicit about the response format or address lifetime, but an agent has enough information to invoke and sequence the tool correctly.

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 tool has zero parameters and an empty input schema, so no parameter documentation is needed. The description's reference to a 'returned address' is sufficient context for how the result is used even though the response schema is absent.

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 a specific verb and resource: 'Create a disposable test address for a full email deliverability audit.' It clearly distinguishes the create step from the companion get_mailtest_result tool and enumerates the audit's scope, so an agent knows exactly what this tool produces.

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 two-step workflow: call this tool, then have the user send an email, then call get_mailtest_result. It does not explicitly state when not to use sibling tools like check_blacklist or whois_lookup, but the full-audit purpose is enough to guide selection in most cases.

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