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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the agent knows this is a destructive write. The description adds the useful scope guarantee ('every other document stays'), which nothing in the annotations provides, but stays silent on reversibility, immediacy, or whether the underlying Drive file is touched or just the assistant's send list.

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 sentence, front-loaded with the action and tightly scoped by a semicolon clause. Nothing wasted and no ambiguity introduced by extra prose.

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 destructive, single-target mutation the basics are present (what is removed, how it is identified, that others survive), and annotations carry the safety profile. Missing is whether the removal is reversible or permanent and whether the Drive file itself is affected — meaningful gaps for a destructiveHint tool.

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 coverage is 50%: the required `link` param has no schema description, but the description supplies it ('by its Drive link'), and `brand` is documented in the schema including its omission rule. Combined, both params are covered, so the description compensates for the schema gap.

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 (stop sending) and a specific resource (one document), scoped by Drive link, and explicitly contrasts with the sibling save_document/link_document family by noting 'every other document stays.' An agent can tell unambiguously this is a single-item removal.

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 scope clause 'every other document stays' implicitly signals this is the per-document removal rather than a bulk operation, but the description never names an alternative (e.g., save_document for edits) or states prerequisites. Usage is inferable but not spelled out.

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