create_domain

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

With no annotations, the description carries the full disclosure burden, and it does add real value by stating the post-creation state: the domain cannot send production mail until DNS is applied and verified. It says nothing about auth requirements, idempotency/duplicate-domain behavior, or rate limits, so the safety profile remains underspecified.

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 short sentences, both earning their place: the first defines the action, the second front-loads the critical follow-up constraint. No redundant restatement of the title or schema.

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 two-parameter creation tool with no output schema and no annotations, the description supplies the action plus the essential downstream workflow constraint. Only edge-case behavior (duplicate domains, errors, immediate usability of the returned domain) is missing, which is a minor gap.

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 coverage is 100% with both parameters documented, including an example for 'name', so the schema already carries the semantics. The description adds no meaning beyond the schema for 'inbound_enabled' or the domain-name format, making 3 the correct 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?

States a specific verb and resource ('Add a sending domain'), which clearly separates it from list_domains, apply_domain_dns, and verify_domain. It does not name those siblings explicitly, but the second sentence implies this is the first step of a multi-step domain workflow.

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 conveys central context — that this is the provisioning step whose DNS must still be applied and verified — which implicitly routes the agent to apply_domain_dns/verify_domain next. However, it never names an alternative or states when NOT to use this tool, so usage is only implied rather than explicit.

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