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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered elsewhere. The description adds real context: results are scoped to the caller's own labels and include colour. It does not disclose pagination, ordering, or volume limits.

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 padding. It is efficient, but its brevity is close to under-specification given the undocumented mailbox parameter.

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 simple read-only list tool with annotations and no output schema, the description is adequate on scope and return content but leaves the single parameter's semantics unexplained. That is the one gap an agent actually needs filled before calling it correctly.

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 has one parameter, 'mailbox', with 0% schema description coverage, and the description never mentions it. The caller cannot tell whether omitting it lists labels across all mailboxes, or whether passing it scopes the results to a single mailbox.

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 names the resource ('the caller's mail labels') and one attribute (colour), which implies a listing operation, but it never states a verb. It also does nothing to separate the tool from siblings like 'intake_list_labels' or 'mail_create_label'.

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 when-to-use guidance, no prerequisite, and no reference to an alternative. The agent must infer that this is the read path for labels, and whether 'mail_create_label' or 'mail_label' complement it, from the name and the sibling list alone.

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