list_domains

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

With no annotations, the description carries the responsibility for behavioral disclosure. It states that listing is scoped to the account and covers every registered domain, but it does not mention the return format, ordering, pagination, or whether unverified domains are included. For a listing operation this is adequate but not rich.

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?

The description is one concise sentence that wastes no words. It front-loads the action ('List') and immediately defines the scope ('every domain registered to this Mektup account').

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 zero-parameter listing tool, the description is sufficient to invoke the operation correctly. It lacks an output schema, so it could have described the expected response shape, but this is more a gap in the environment than in the description itself. The coverage is strong for a simple list-all 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?

The tool has zero parameters, and the schema has no properties, so the description does not need to explain parameter semantics. The baseline of 4 applies, and the description correctly implies no arguments are needed.

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') and a clear resource ('every domain registered to this Mektup account'), making the tool's function immediately obvious. It is clearly distinguished from sibling tools like create_domain, delete_domain, and get_domain_records, which operate on individual domains or domain settings.

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 clear context: this tool enumerates all domains on the account. It does not explicitly mention alternatives or exclusion criteria, but the operation is so simple and distinct from siblings that the intended usage is unambiguous.

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