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

With no annotations provided, the description carries the disclosure burden. It adds useful behavioral context by specifying 'active receive-only' and account scope, but it does not describe ordering, pagination, return shape, or what 'active' or 'receive-only' mean in practice.

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?

One short, front-loaded sentence with no wasted words. Every term in the description adds meaning and helps disambiguate the operation.

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 zero-parameter list tool with no output schema, the description is complete enough. It states the resource, the operation, the filter ('active receive-only'), and the scope ('for the account'). No additional input guidance is needed.

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 are no parameters, so the schema and description have nothing to document. The description's scope statement is sufficient for a zero-parameter list operation, matching the baseline of 4.

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') and resource ('inboxes'), and adds scope qualifiers ('active receive-only', 'for the account'). This clearly distinguishes it from sibling tools like inbox_get, inbox_messages_list, and inbox_create.

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 context is clear: use this to list the account's active receive-only inboxes. It does not explicitly name sibling alternatives or exclusion conditions, but the qualifiers and zero-parameter nature make the intended usage apparent.

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