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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world, covering the safety profile. The description adds useful behavioral detail — results are alphabetically ordered and include message counts — but says nothing about pagination behavior or result size limits, so it is a modest supplement rather than rich disclosure.

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?

A single front-loaded sentence with no filler; the scope, ordering, and payload are all packed in efficiently.

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 an output schema present, return values need not be spelled out, and the description still notes the shape of the result (labels with counts). It omits any hint about pagination semantics, but for a simple paged list tool the sentence covers what an agent minimally needs.

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 50%: cursor and prefix are documented in the schema, while limit and inbox_id are not. The description covers the inbox scoping that inbox_id represents but says nothing about the limit cap or the case-sensitive prefix filter, so it does not compensate for the uncovered half of the parameters.

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?

States a specific verb (find/list), a specific resource (labels), and the scope (used in an inbox), plus ordering and returned data (alphabetical, with message counts). It is clearly distinguishable from the sibling label tools, which are all update/bulk-update operations rather than lists.

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 use this tool, when to prefer an alternative, or any prerequisite (e.g. needing inbox_id first). Usage is only implied by the sentence describing the resource, so an agent gets no routing guidance beyond the obvious.

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