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

Annotations cover the safety profile (readOnly=false, idempotent=true, destructive=false, openWorld=true), and the description adds genuinely useful behavior: it returns the DNS TXT record for ownership verification and the A record target pointing to the Caddy edge for automatic on-demand TLS. With no output schema, this return-value disclosure is valuable context beyond the annotations.

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 tightly written sentences: the first front-loads purpose and the two target modes, the second delivers the return behavior. Zero filler and nothing redundant with the structured fields.

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 non-read-only, open-world mutation with no output schema, the description compensates well by explaining the return records and the TLS setup, plus the ownership requirement. It stops short of describing verification ordering or failure/conflict behavior, which leaves 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%, so both parameters are already documented, giving a baseline of 3. The description reinforces that the domain must be owned/controlled but adds no syntax, format, or constraint details 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 (Attach) and resource (custom domain to an agent), and further differentiates the two supported targets: a live tunnel or a published miniapp served over HTTPS. An agent can tell this apart from list_domains, verify_domain, and remove_domain from the sentence alone.

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 the general context (attaching an owned domain) but never explicitly says when to call this before/after alternatives such as verify_domain or remove_domain, nor states prerequisites or ordering. Usage is implied by the ownership-verification mention rather than spelled out.

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