add_domain

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

With no annotations, the description must disclose behavior on its own. It conveys the critical fact that adding does not activate the domain—activation requires a separate verify_domain call. However, it lacks other behavioral detail such as duplicate handling, domain ownership requirements, or side effects of setting isPrimary, which are relevant for a mutation tool.

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 exactly two sentences, front-loaded with the primary action and immediately followed by the next-step instruction. There is no filler or repetition, making it a model of concise, structured tool documentation.

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 the tool's simplicity (4 parameters, only 1 required) and complete schema coverage, the description covers the essential operational context: it adds to the active brand and requires later verification. It could explicitly state that the domain starts inactive, but this is logically implied by the verify_domain instruction. Overall, it is sufficient for correct usage.

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%, so the baseline score applies. The description's phrase 'to the active brand' echoes the brandId parameter's documented default behavior, adding no new meaning beyond what the schema already provides. The other parameters (domain, isPrimary, primaryContentType) are fully described in the schema without further elaboration needed.

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 with a specific verb ('Add') and resource ('custom domain to the active brand'), immediately distinguishing it from sibling tools like list_domains, verify_domain, and delete_domain. The instruction to call verify_domain afterward reinforces its role as the creation step.

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 provides explicit workflow guidance: 'After adding, call verify_domain to check DNS and activate it.' This tells the agent when to use this tool as the first step in a multi-step process. However, it does not explicitly state when not to use it or mention alternative tools, so it stops short of full specificity.

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