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

Without annotations, the description carries the burden of behavioral disclosure. It states 'Read' implying a non-mutating operation, and 'Owners only' indicates access control. However, it does not elaborate on permission errors, side effects (though likely none), or the return structure. The 'Owners only' clause adds context but could be more explicit about consequences of unauthorized access.

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 concise sentences with no filler. The core action and data scope are front-loaded in the first sentence, and the access restriction is stated in the second. Every word earns its place.

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 tool with one optional parameter and no output schema, the description lists the types of data returned (expiry dates, renewal status, spending limits, billing problems) but does not explain the output format or whether it applies to all domains in the workspace. This is adequate but leaves minor gaps about expected results.

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 schema describes the workspace parameter with 100% coverage, so the schema already provides meaning. The description adds no additional semantics about how the parameter affects results (e.g., scoping to a specific workspace or listing all domains). This matches the baseline of 3 for high schema coverage.

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 clearly states the action ('Read') and the resource (domain expiry dates, renewal status, spending limits, billing problems). It distinguishes itself from sibling tools like domain_renewal_set (which implies mutation) and domain_buy by focusing on reading renewal-related data. However, it doesn't explicitly name an alternative, so it's not 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?

No guidance is given on when to use this tool versus alternatives such as domain_renewal_set or domains_list. The description implies it is for reading, but it doesn't explicitly state the condition for using it (e.g., 'when you need to check renewal status') or exclude other tools. This leaves the agent to infer usage from the verb alone.

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