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

Annotations already flag destructiveHint=true and idempotentHint=true, but the description adds the blast radius that annotations cannot express: senders on the domain can no longer send. It also restates irreversibility ("can't be undone") and the two-step preview/confirm gate, which is exactly the operational context an agent needs before a destructive call.

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?

Two sentences with no filler. The destructive consequence is front-loaded before the mechanical requirement (domain_id) and the confirmation protocol, which is the right order for a risky operation.

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 three-parameter destructive tool with full schema coverage and annotations covering readOnly/destructive/idempotent hints, nothing essential is missing: consequence, irreversibility, required identifier, and the preview-confirm flow are all present. No output schema exists, so return-value detail is not needed.

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%, and the confirm and dry_run parameters are already documented in detail in the schema, including the preview-then-confirm instruction. The description only restates that domain_id is required and echoes the confirm semantics, so it does not add meaning beyond the structured fields.

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?

"Delete a sending domain" names a specific verb and a specific resource, which separates it cleanly from sibling mutations such as delete_sender, delete_list, delete_tag and from the non-destructive get_domain/list_domains/update_domain. An agent can identify the target object and operation without opening the 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?

The description supplies a concrete calling workflow: pass domain_id, call without confirmation to get a preview, then re-call with confirm: true. That is real guidance on how to invoke it. It stops short of stating when not to delete (for example, when update_domain or verify_domain would be the better move), so no explicit alternative is named.

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