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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It conveys that this is a read-only listing containing a state snapshot, but it omits pagination behavior, ordering, whether domains in all states (unverified/failed) are included, and what the response structure looks like. For a tool with zero annotation support, this is a notable gap.

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?

An eight-word sentence with the verb front-loaded and zero filler. Every word earns its place by naming the action, the resource, and the distinguishing data content.

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 very simple tool (one required parameter, no enums, no nested objects), the input side is fully covered by the schema and the description states the core output content. However, with no output schema and no annotations, the meaning of 'last observed state' and the shape of the returned list remain undefined — adequate but with clear gaps.

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% — the single parameter organization_id is already documented as 'Active organization ID' in the schema. The description adds no parameter-level meaning, so the baseline of 3 applies.

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 uses a specific verb ('List') with a clear resource ('sending domains') and adds a distinguishing detail ('last observed state'). It is implicitly differentiated from the many singular-domain siblings (domain_create, domain_get, domain_verify, domain_report) by its plural, listing-oriented framing, though it never names an alternative explicitly.

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 provides no guidance on when to use this tool versus its six domain-related siblings. There is no mention of alternatives, exclusions, or the condition under which an agent should pick, say, commsharbor_domain_get over commsharbor_domains. Usage is only trivially implied by the verb 'List'.

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