Create Domain

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

Annotations indicate idempotentHint=true and readOnlyHint=false, but the description adds value by clarifying that the tool creates DNS records and verification state, which is a meaningful behavioral detail beyond what annotations provide. No contradictions.

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, no waste. The first sentence states purpose, the second clarifies scope and key behavioral effect. Front-loaded and efficient.

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?

Tool has moderate complexity (2 params, 1 required) and an output schema (not shown) that likely documents return values. Description covers the core action and outcome; missing minor details like whether it returns a domain ID or status, but output schema may cover that.

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%, with both parameters already well-described in the input schema (name regex/length, idempotency_key optionality). The description does not add additional parameter-level meaning 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 verb 'Add' and the resource 'existing domain', and distinguishes what it does not do (purchase) and what it does (create DNS records and verification state). This differentiates it from siblings like shipmail_verify_domain and shipmail_delete_domain.

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 the domain must already be owned ('Add an existing domain') but does not explicitly state prerequisites, when to use this versus alternatives (e.g., shipmail_verify_domain for verification), or potential failure cases. Usage guidance is only implied.

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