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

Annotations already declare openWorldHint=true, idempotentHint=false and destructiveHint=false, but the description adds high-value context the annotations cannot: the send is irreversible ("Mail cannot be taken back") and it uses the last saved state rather than pending edits. It still doesn't describe failure modes (which addresses are silently skipped is only in the schema).

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?

Three tight sentences with the recipient scope front-loaded, then the irreversible-action warning, then the preview escape hatch. Every clause carries information.

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 an irreversible outbound send with no output schema, the description covers destinations, source state, irreversibility and the dry-run path. It leaves the return value and post-send confirmation behavior unstated, but nothing essential to calling it correctly is missing.

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 all five parameters are already documented, which sets the baseline at 3. The description reinforces the relationship between `send_to`, `members` and `preview`, but adds no syntax or format detail beyond the schema.

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 (sends/emails) and resource (the workbook, as last saved) and names the recipient set precisely, deferring to configure_workbook's `members` and the `send_to` override. An agent can tell this apart from share_workbook or link_workbook without opening a schema.

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?

Gives a clear operating instruction — confirm recipients with the user first because mail is irreversible — and points to `preview` for a dry run. It does not explicitly contrast with the sibling share_workbook, so it stops short of naming alternatives.

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