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

No annotations are provided, so the description carries behavioral burden. It usefully discloses a non-obvious behavior: `status` reflects the last observed SES/DNS state and does not become `active` merely because provisioning was requested. However, it does not go further to describe response shape, pagination, or error behavior, though 'List' implies a read-only operation.

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, front-loaded with the primary action, and no filler. The second sentence earns its place by explaining the potentially surprising meaning of `status`. Every word contributes.

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 one-parameter list tool with no output schema, the description adequately conveys the return concept and the key status caveat. It could be more explicit about the exact output fields or pagination, but nothing essential is missing for correct 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?

The single parameter `organization_id` is already fully described in the schema as 'Active organization ID,' giving 100% schema coverage. The tool description adds organizational context but no additional parameter-level semantics, so the schema-based baseline of 3 is appropriate.

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 opens with a specific verb and resource: 'List sending domains with their last observed state.' The plural 'domains' and the listing verb clearly distinguish it from singular or operation-specific siblings like commsharbor_domain_get and commsharbor_domain_verify. The added status clarification reinforces what the tool returns.

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 makes the usage context clear: this is the tool for enumerating sending domains and checking their observed state. It does not explicitly mention alternatives or when not to use it, but for a simple list tool the intended use is unambiguous.

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