create_inbox

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

With no annotations, the description carries the full burden. It discloses useful behavioral detail (auto-assign to available domain if domain_id omitted; no DNS setup needed) but does not cover failure modes, uniqueness constraints, or confirmation behavior. While it adds value, a more complete picture would improve safety and predictability for a write operation.

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 well-structured with a lead statement, a concise explanation of the auto-assignment behavior, and a clear list of argument meanings. No word is wasted. Each part earns its place and the format is easy to parse.

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?

Given the tool's complexity (5 params, one required) and the presence of an output schema, the description provides near-complete invocation guidance. It covers all params, the core behavior, and a deployment nuance. It doesn't detail return values (output schema likely covers that) but is otherwise adequate for correct use.

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 coverage is 0% (no parameter descriptions in schema), but the description thoroughly documents all five parameters, including examples (e.g., local_part as 'support', 'billing', display_name as 'Support Agent'). It explains the role of `name` as a fallback for display_name and clarifies `domain_id` is optional, which is exactly the semantic information the schema lacks.

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's purpose: 'Create a new inbox for receiving emails.' It also provides the resulting email address format, distinguishing this tool from siblings like list_inboxes or create_domain. The verb is specific ('Create') and the resource is well-defined.

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 clear context for when to use this tool (when you need a new inbox) and includes a key benefit ('no DNS setup required'). It doesn't explicitly mention alternatives or exclusion cases, but the purpose is distinct enough from sibling tools, and the auto-assignment note helps the agent decide when to omit domain_id.

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