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

Annotations already declare destructive=true and idempotent=true, so the bar is lower, but the description still adds real value: it discloses that the domain is removed from both the Vercel project and Sitelas's records, that the *.sitelas.com address keeps working, and that the owner must remove DNS at the registrar afterwards. The confirm: true requirement is also surfaced.

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?

A single dense sentence that is front-loaded with the core action, then the reasons, then the confirm requirement, then the post-action note. It's slightly long but nearly every clause carries meaning.

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?

With no output schema and annotations covering safety, the description supplies the missing operational context: what remains working, what the caller must do after (DNS at registrar), and what Sitelas cannot do. Enough to call it correctly, though a hint about verifying removal isn't included.

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% and all three parameters are documented in the schema, so baseline is 3. The description reinforces the confirm requirement and the apex+www scope but adds little syntax or format detail beyond what the schema already provides.

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+resource pair (detach/delete a custom domain from a site) and clarifies the apex + www scope. It is clearly distinguishable from sibling tools like set_custom_domain and check_custom_domain without opening their schemas.

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?

Names concrete situations that select this tool — a typo'd domain, swapping to another domain, or stopping serving a hostname — which gives the agent clear usage context. It stops short of explicitly naming set_custom_domain as the swap alternative, so it's a 4 rather than a 5.

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