list_sending_domains

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

With no annotations, the description carries the burden of behavioral disclosure. It explains the output format ('verification status and DNS records'), notes that each record shows currently published values, and frames the tool's diagnostic value. The read-only nature is implied by 'List' and the diagnostic framing.

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?

Two sentences with no filler. The core listing behavior is front-loaded, and the second sentence adds valuable diagnostic context without redundancy.

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 zero-parameter list tool with no output schema, the description fully covers what the agent needs to know: what is returned, what records show, and when the tool is useful. Nothing important 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 has zero parameters, so the description needs to provide no parameter-level detail beyond what the empty schema shows. This meets the baseline for parameter-free tools.

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 ('List') and resource ('sending domains'), and clarifies the output includes verification status and DNS records. It also distinguishes itself from sibling tools like add_sending_domain and verify_sending_domain by focusing on listing and diagnosis.

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?

Clearly implies use when you need to see sending domains, their verification state, or diagnose a stuck verification. It doesn't explicitly contrast with verify_sending_domain, but the diagnostic purpose is specific enough to guide selection.

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