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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so "Read-only" is largely redundant. The description does add genuine behavior context by indicating the response contains multiple inboxes and that message requests are flagged with pending: true, which is helpful since there is no output schema.

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 short sentences, front-loaded with the resource definition. The trailing "Read-only." duplicates the annotations and is the one piece of low-value wording.

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 single-parameter read tool with no output schema, the description covers what is returned at a high level but leaves the sole parameter unexplained and gives no sense of result volume or ordering. Adequate but with a clear gap given zero schema coverage.

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?

There is one parameter, account_id, with 0% schema description coverage, so the description must carry the meaning. "The account's inboxes" only weakly implies account_id selects the account; it never states that a UUID account identifier is required or what happens if it is omitted.

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?

Names a specific resource ("The account's inboxes") and its scope, with concrete examples (main inbox, message requests) so an agent can distinguish it from sibling list tools like list_messaging_chats or list_chat_requests. It lacks an explicit verb, but the resource is unambiguous.

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?

Offers no when-to-use or when-not-to-use guidance and names no alternative tools. The only implied usage signal is that message requests appear as inboxes with pending: true, which hints at how to interpret results rather than when to call the tool.

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