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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so safety is covered. The description adds value beyond that by naming what data comes back for each inbox (ticket vs. file-store mode, renewal timing) and that the call is free — useful context an agent wouldn't get from 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?

Extremely short and front-loaded, with no filler. The phrasing is a noun-phrase fragment rather than a complete sentence, which is slightly awkward, but nothing in it is wasted.

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?

With no parameters, no output schema, and annotations covering the safety profile, the description's main job is to say what the list contains — which it does by naming the per-inbox attributes. A little more on ordering or whether all inboxes are returned would make it complete, but the essentials are present.

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?

The tool takes zero parameters and has no schema properties, so there is nothing for the description to clarify. Baseline for a parameterless tool 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?

The description identifies the resource (this account's inboxes) and the attributes surfaced for each one — ticket-opening behavior vs. attachment saving, plus renewal date. It lacks an explicit verb, but the title 'List inboxes' plus the attribute list makes the operation unambiguous relative to siblings like email_create_inbox or email_update_inbox.

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?

There is no statement of when to call this versus alternatives (e.g., email_update_inbox for configuration changes or ticket_connect_inbox for wiring an inbox to help desk). The only hint is the trailing 'Free.', which signals cost but not usage context.

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