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

With no annotations, the description carries the full burden. It implies a read-only operation via 'List', which is non-destructive and safe, and mentions the output includes verification status. However, it does not disclose potential pagination, ordering, default limits, or any required permissions. Adequate for a simple list 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 a single, concise sentence with no wasted words. It is front-loaded with the action ('List') and includes the most relevant detail (verification status) with maximum efficiency.

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 tool with no parameters, no annotations, and no output schema, the description adequately conveys the tool's purpose and the nature of its return (domains plus verification status). It could mention whether the list is paginated or filtered, but the simplicity of the tool makes this sufficient.

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 is empty, so the description does not need to explain parameters. Baseline for 0 params is 4; the description adds no param information, which is appropriate since none exist.

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 'List all configured sending domains with their verification status' uses a specific verb ('List'), a clear resource ('configured sending domains'), and adds the key detail of including verification status. This cleanly distinguishes it from sibling tools like list_email_accounts or get_domain_verification_status.

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 only what the tool does, with no guidance on when to use it compared to alternatives such as get_domain_verification_status or list_email_accounts. There is no mention of prerequisites, exclusions, or preferred scenarios, so the usage context is entirely implicit from the tool name.

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