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

Annotations already declare read-only, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds genuinely new context: an API token is required, the meaning of each state (including that verification_lapsed pauses monitoring), and the instruction to relay next_step verbatim rather than paraphrase it.

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?

Front-loads the trigger condition before the output description, and every clause carries information — the parentheticals exist to define the state values. It runs slightly long in a single breath, but nothing is redundant or restated.

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?

With an output schema present, return fields need not be explained, yet the description still glosses the two important ones (state and next_step) and covers auth. Nothing an agent needs to call and interpret this 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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; the schema is trivially complete at 100% coverage. Baseline 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?

States a specific verb and resource ('Lists every domain on the caller's account') and scopes it to the caller's own account, which separates it from sibling tools like get_domain_records or check_domain_verification that operate on a named domain. The enumerated state values (verified, pending, verification_lapsed) make the output shape predictable before 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?

Gives an explicit trigger: use when a signed-in operator asks which domains their account monitors, or what to do next on them. It does not name a competing sibling or state when-not-to-use, but the caller-anchored condition is specific enough that an agent will route here correctly.

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