Create a temporary email address

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

Goes well beyond the annotations by disclosing quota cost ('Uses 1 unit of the account's mailbox quota'), noting that reading mail is free, and stating addresses 'never expire' so deletion is required. These are meaningful operational traits the annotations (readOnlyHint=false, idempotentHint=false, openWorldHint=true) do not convey.

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?

Three short sentences, front-loaded with the core purpose, then cost, then lifecycle. Every sentence carries distinct information with no redundancy or 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?

An output schema exists, so return values need not be described. The description covers the essential non-schema facts an agent needs: quota impact, non-expiry, deletion requirement, and the follow-up tool for receiving mail.

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%, with 'name' and 'domain' fully documented in the schema, including the 'leave empty for random' behavior and the list_domains reference. The description adds no parameter detail beyond what the schema already provides, so the baseline of 3 applies.

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?

States a specific verb and resource ('Create a new temporary email address') plus a scope note that it can receive mail immediately. This clearly distinguishes it from siblings like list_mailboxes, delete_mailbox and the message-reading tools.

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?

Provides explicit lifecycle guidance: 'call delete_mailbox when it is no longer needed' and 'use wait_for_message to get the mail it receives.' It routes the agent to the right follow-up tools, though it doesn't explicitly say when not to use this tool or name a competing alternative (there is no sibling create tool).

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