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

Annotations already communicate destructive behavior via destructiveHint: true and readOnlyHint: false, so the bar for additional disclosure is lower. The description adds scope context—deleting multiple emails from one mailbox—but does not disclose whether the deletion is permanent, reversible, or how failures are handled.

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, front-loaded sentence with no filler or repetition. Every word earns its place, and the key facts—bulk, resource, and mailbox scope—are stated immediately.

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 two-parameter bulk delete tool with an output schema and destructive annotation, the description is nearly complete. It could be stronger by explicitly noting permanence or naming the single-delete sibling, but nothing essential is missing for basic invocation.

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 100%, so the params are already documented. The description adds useful relational meaning beyond the schema by clarifying that the deletion targets several mail IDs within one mailbox, tying ids to mailboxId. It stops short of explaining ID formats or edge cases like empty arrays.

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 ('Delete'), a clear resource ('several emails'), and a scope ('of one mailbox at once'). This clearly distinguishes it from mails.delete (single mail) and from bulk operations on other resources such as attachments.delete_bulk.

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 phrasing 'several emails of one mailbox at once' implies the intended use case: batch-deleting multiple mails within a single mailbox. However, it does not explicitly mention when to avoid this tool, such as for deleting a single mail, nor does it name mails.delete as the alternative.

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