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

Annotations already declare destructiveHint=true, idempotentHint=true, and openWorldHint=false, so the safety profile is covered. The description adds genuinely non-redundant context by disclosing the side effect on the other domains ('the others redirect to it'), which the annotations do not express. It stops short of saying what happens to the previously-primary domain or whether the target must be verified.

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?

One short sentence with the primary action front-loaded and the consequence appended; no filler, no restating of the title verbatim.

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 one-parameter mutation with annotations covering destructiveness and idempotency and no output schema, the description is largely sufficient: the action and its effect on sibling domains are both stated. Minor gaps remain around whether the prior primary is demoted and whether the change is reversible, but nothing essential is missing.

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?

There is a single parameter with 100% schema description coverage ('Help center domain id.'), so the schema carries the detail. The description adds no extra meaning about where the id comes from or any format constraints, making the baseline 3 appropriate.

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 ('Make ... the main address') and resource (help center domain), and the phrase 'the others redirect to it' makes the promotion semantics unambiguous. An agent can distinguish this from add_help_center_domain, remove_help_center_domain, and list_help_center_domains without opening any schema.

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 describes the operation but gives no when-to-use, prerequisites, or alternatives (e.g., that a domain must first exist via add_help_center_domain, or that list_help_center_domains supplies the required id). Usage is only inferable from the tool name.

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