create_mailbox

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

With no annotations, the description fully discloses behavioral traits: it states non-idempotency, surfaces conflict/cooldown/limit errors, and mentions conditional return of mailbox_settings and next_actions. This provides good transparency beyond creation.

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 concise with four short sentences, each adding distinct value: creation action, address format, conditional return, and non-idempotency warning. No redundancy or fluff.

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 covers creation, constraints, and error conditions but lacks detail on return structure beyond the conditional scenario. It does not explain what mailbox_settings or next_actions contain, leaving some ambiguity for the agent. Overall adequate but not exhaustive.

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?

Input schema covers both parameters with descriptions, so baseline is 3. The description adds the specific address format (<slug>@<project-mail-host>.mail.run402.com) and clarifies cross-project allowance, which goes beyond the schema's parameter descriptions.

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 states the tool creates a project-scoped mailbox local part, specifies the resulting address format, and distinguishes from sibling tools like 'update_mailbox' or 'delete_mailbox' by emphasizing creation and cross-project slug allowance.

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 does not explicitly state when to use this tool versus alternatives. It only implies creation usage and mentions error conditions, but lacks guidance on when not to use it or how it differs from other mailbox-related tools like 'set_mailbox_defaults'.

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