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

With no annotations provided, the description carries the burden of behavioral disclosure. It implies a read-only operation by saying 'List' and indicates the response scope is 'metadata', which is useful. However, it does not mention pagination behavior (despite limit/offset parameters), ordering, possible errors, or authentication requirements, so transparency is only partial.

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 a single, concise sentence with no redundant words. It front-loads the action and resource, making it easy to parse quickly. Nothing should be removed or added without sacrificing clarity.

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 tool with three parameters, no output schema, and no annotations, this description is too sparse. It does not define what 'message metadata' includes, how limit/offset work, or what the response structure looks like, so an agent lacks critical information for correct invocation and result interpretation.

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 0%, and the description does not explain any parameter. It fails to compensate for the schema's lack of descriptions; the agent must infer the meaning of inboxId, limit, and offset solely from their names. This adds no value beyond the raw schema.

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 states a specific verb ('List') and resource ('message metadata for an inbox'), which clearly identifies the tool's operation and distinguishes it from sibling tools like inbox_list (lists inboxes) and inbox_message_get (retrieves a single message). The term 'metadata' also separates it from inbox_message_raw, which would return full raw content.

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 usage: use this tool when you need to list message metadata for a specific inbox. However, there are no explicit when-to-use or when-not-to-use instructions, nor any mention of alternatives or pagination best practices, leaving usage guidance mostly to inference from the tool name and description.

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