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

Goes well beyond the annotations by disclosing the 4-changes-per-month quota, that the old domain stops answering, the no-op case when the domain is unchanged, and the domain_taken refusal. The destructiveHint=true annotation is corroborated rather than merely repeated, and the credential/lifecycle context is spelled out in the schema.

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?

Front-loaded with the action and its consequence, then prerequisites, then side effects, then args/returns. Dense but purposeful; the multi-clause prerequisite sentence is the only mildly heavy part.

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 destructive, open-world mutation with no output schema, it covers preconditions, quota and irreversibility, error outcomes, and the shape of the return ({ custom_domain }). An agent can execute and report back without further discovery.

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 the schema description already states 'no http(s)://, no path' and the www. normalization, so the description's domain note is largely duplicative. No additional syntax or validation detail is added beyond what the schema carries.

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 ('Connect the help center to the user's own domain'), and distinguishes itself from the read counterpart by naming helpcenter_get_custom_domain as the follow-up. The DNS/certificate explanation makes the side effect concrete rather than abstract.

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?

Explicitly names the prerequisites (claimed help center, verified email, activated plan) and what to do when they are unmet (read the capability_locked next step). It also gives a negative rule — only set the domain the user asked for — and routes to helpcenter_get_custom_domain afterwards.

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