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

Annotations already declare destructiveHint=true and idempotentHint=true, so the description's job is to explain the mutation's side effects, which it largely does not. It adds useful plan and verification prerequisites but never warns that setting is_default appears to demote the previously default domain, nor whether omitted fields are left untouched.

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 front-loaded sentence lists the operations, followed by two short prerequisite clauses. Every phrase carries information and nothing is padded.

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 four-parameter mutation with no output schema, the description covers operations and preconditions but omits the destructive side effect the annotation advertises and partial-update semantics. An agent knows what it can change, but not fully what changing it will do.

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 each of the four parameters already carries a description, so the schema does the heavy lifting. The description only restates the three settable fields at a high level and adds no format, validation, or interaction detail beyond it.

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 gives a specific verb ('Update settings') plus the resource ('a verified custom domain') and enumerates the three mutable settings (default flag, 404 redirect URL, cloaking). The 'verified'/'must be active' wording implicitly separates it from add_domain, verify_domain, and activate_domain, though it never names them.

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?

Preconditions are explicit: Pro plan or higher and a domain that is already verified and active, which tells the agent when this tool is applicable. It stops short of explicitly routing the agent to verify_domain or activate_domain when the precondition fails.

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