Create a mailbox

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

Discloses quota consumption and error condition (400 if domain not verified), adding value beyond annotations that indicate destructiveHint and idempotentHint. Does not mention idempotency behavior when mailbox already exists.

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 efficient sentences covering purpose, behavior, and usage guidance without redundancy. Every sentence adds value.

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?

Covers purpose, usage boundaries, behavioral consequences, and parameter prerequisites. Lacks mention of return value or error handling for duplicate mailbox creation, but overall sufficient for a creation tool.

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 has 100% coverage, but the description adds practical context about domain validation and quota impact, helping the agent understand parameter implications beyond schema definitions.

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?

Clearly states 'Create a new mailbox' and specifies the resource and action. Explicitly distinguishes from lookup tools with 'do NOT call this just to look one up.'

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 when to use ('when the user explicitly asks to create/add/make a mailbox') and when not to ('do NOT call this just to look one up'). Also mentions prerequisite condition for custom domains requiring DNS verification.

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