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

The annotations already establish that this is a safe, read-only, idempotent, non-destructive operation. The description adds practical behavioral context beyond the annotations by disclosing the `full_access` API key requirement and the underlying `GET /domains` endpoint. It does not mention rate limits or pagination behavior, so a 4 rather than 5.

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 two short sentences and front-loads the core purpose before the auth and endpoint details. Every sentence provides useful information, with no padding or repetition.

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 read-only list tool with full parameter documentation and complete annotations, the description supplies the key missing context: auth requirements and the API endpoint. It is nearly complete, though it could mention pagination behavior for extra clarity.

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 three pagination parameters (`after`, `limit`, `before`) are fully documented in the schema. The description adds no parameter-specific meaning beyond what the schema already provides, so the 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 uses a clear verb+resource phrase, "List domains," and provides the backing endpoint `GET /domains`, so the operation is unambiguous. It does not explicitly distinguish itself from sibling tools such as `get_domain` or other `list_*` tools, which keeps it below a 5.

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 states the prerequisite "Requires a `full_access` API key," which is useful usage context. However, it does not say when to choose this tool versus alternatives like `get_domain` or explain pagination behavior, so usage is only implied by the name and endpoint.

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