Declare a sending domain

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

The description adds the crucial non-obvious behavior that declaration does not authenticate and DNS changes require a human step, so the agent must not claim readiness. Annotations already signal a write operation; this description adds meaningful operational context.

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?

Three tight sentences, front-loaded with the action and output, followed by the critical caveat. No filler or 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?

Given no output schema, the description does a good job of stating that DNS records are returned and what to do with them. It could mention failure states like duplicate domains, but the core invocation and follow-up workflow are adequately covered.

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 schema covers domain and dkim_selector with descriptions, and idempotency_key is self-explanatory by name. The description does not explain how the optional parameters affect DNS records, but this is a moderate gap given 67% schema coverage.

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 action ('Declare a domain') and a concrete output (DNS records to add, each with purpose). It explicitly separates declaration from authentication and verification, which distinguishes it from siblings like vaemail_verify_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 context is clear: this is the initial declaration step, and the follow-up is publishing DNS records and verifying. It does not explicitly name alternatives or say when not to use this tool, but the verify-later guidance makes the intended workflow evident.

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