Create a disposable email inbox

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

With no annotations provided, the description carries the behavioral burden, and it does well: it states that the inbox is temporary, can receive mail, and that the response includes the address and expiration time. It does not cover every operational detail such as cleanup or duplicate-name behavior, but the essential lifecycle is disclosed.

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 three tight sentences: the core action, the usage context, and the return value. Every sentence adds information, and there is no redundant or filler content.

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 simple create tool with no required parameters and no output schema, the description covers what the tool does, when to use it, and what the response contains. It could mention interactions with sibling tools or what happens if a requested domain/username is unavailable, but those are minor gaps given the schema already documents allowed values.

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 already provides 100% coverage of both optional parameters, including the allowed characters for username and the fact that domain comes from list_domains. The description adds no parameter-specific meaning, so it stays at the baseline expected when the schema is fully documented.

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 names a specific action and resource: creating a temporary email address that can receive mail. It also clarifies the intended use case (signups, trials, avoiding real addresses), which makes the tool's role unambiguous compared to siblings like list_messages, delete_inbox, and wait_for_email.

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 explicitly says when to use the tool: when the user needs an email address for a signup, trial, or similar situation. It does not mention alternatives or exclusions, but because this is the only creation-focused sibling, the guidance is still clear and actionable.

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