List Domains

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

The readOnlyHint annotation already indicates a safe read operation. The description adds value by disclosing the return contents (domain names, statuses, regions, capabilities) and a user-interface guideline ('Don't bother telling the user the IDs unless they ask'), which are not present in the annotations. No contradictions detected.

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 sentences, front-loaded with the core purpose, and every clause adds information. The informal instruction about IDs is concise and does not waste words.

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, the description covers what the tool does and what it returns, which is adequate given there is no output schema. It does not explain pagination behavior beyond the schema descriptions, but that is already documented. The extra user-facing guidance adds completeness without being verbose.

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 input schema has 100% coverage with clear descriptions for each parameter (after, limit, before). The description does not add extra parameter semantics, so it meets but does not exceed the baseline.

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 specific verb ('List') and resource ('domains from Resend'), clearly distinguishing it from sibling tools like get-domain or create-domain. It also specifies the returned fields (names, statuses, regions, capabilities), making the purpose unambiguous.

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 implies usage (for listing all domains) but does not explicitly state when to use this over get-domain or when not to use it. There is no mention of alternatives or exclusions, leaving usage guidance to be inferred from context.

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