Attach an external domain the user already owns

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

With no annotations, the description carries full burden and does an excellent job: it discloses the return value (CNAME target + DNS instructions), the status flow (`dns_pending` until propagation), cost (5 credits), and ongoing billing implications (Active Sites $10/site/month). This goes well beyond a minimal description.

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 four sentences and covers action, return value, status, usage guidance, and cost. Each sentence adds value, though it is slightly verbose with the Active Sites detail. Structurally front-loaded with the main action, then supporting details.

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?

The description fully covers the tool's purpose, return value, status behavior, cost, and alternative. It is complete enough for an agent to select and invoke the tool correctly, especially given the detailed schema and no output schema (return value is described).

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% and both parameters are documented in the schema. The description adds no extra parameter-level detail beyond the schema, which is acceptable per the baseline, but it does not enhance understanding beyond the schema.

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 ('Attach a domain the customer already registered elsewhere') and the resource ('to a deployed Warpweb site'). It explicitly contrasts with `register_domain`, distinguishing from a sibling tool.

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?

Provides explicit when-to-use guidance: 'Use this when the customer says I already own the domain' and an explicit alternative: 'versus `register_domain` for new purchases through Cloudflare Registrar.' This is clear and actionable.

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