List PromptJang mailboxes

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

Annotations already establish readOnly, idempotent, and non-destructive behavior. The description adds useful context beyond that: mailboxes are 'durable', scoped to the API key, and the returned IDs serve list_unread and send_event. This supports correct usage without contradicting annotations.

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?

Two concise sentences, both earning their place: the first defines the resource and scope, the second clarifies the return value and downstream consumers. No filler or repetition.

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 list tool with one optional fully-documented parameter, an output schema, and comprehensive annotations, the description is complete. An agent can call it reliably without additional assumptions or missing context.

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%, and the single optional parameter response_format has an enum, default, and description. The tool description does not add parameter-specific meaning, but the schema already carries the full burden, so the baseline score of 3 is appropriate.

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 uses a specific verb ('List') with a clear resource ('durable agent mailboxes available to this API key') and states that it returns registered mailbox IDs for list_unread and send_event. This clearly distinguishes it from sibling tools like list_targets and list_unread, which operate on different resources or actions.

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 implies when to use the tool: to discover mailbox IDs needed by list_unread and send_event. It provides clear usage context, though it does not explicitly state when not to use it or mention alternatives, so it stops just short of full guidance.

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