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

Annotations already cover read-only, idempotent, and non-destructive behavior. On top of that, the description adds the authentication requirement and clarifies that the result is organized by contact role, which is useful behavioral context beyond the schema and annotations.

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 a single tight sentence with no filler. It front-loads the core purpose, names the roles, and adds the two most important operational facts: authentication is required and the result is role-based.

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 tool with one required parameter and full schema coverage, the description covers the essential operational and return information. There is no output schema, so it could be more specific about the exact shape of each contact object, but the current level is adequate for safe 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?

Schema description coverage is 100%, so the schema already fully documents both parameters. The description does not add parameter-level detail, but it also does not need to; it reinforces that the domain parameter determines which contacts are returned.

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: it gets all contacts assigned to a domain and explicitly names the four roles (registrant, admin, tech, billing). This clearly distinguishes it from related tools like getContact and listContacts, which operate at a different level of granularity.

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 clear this is the tool to use when you need the set of role-based contacts for a specific domain, and it notes the authentication requirement. It does not explicitly name alternatives or exclusions, but the domain-scoped purpose is strong enough for an agent to infer when to choose it.

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