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

Annotations already declare destructiveHint=true and idempotentHint=false, but the description goes well beyond them: it names exactly what is destroyed (all existing browser owner sessions), warns that the new key is shown only once and must be retained, and preempts a false assumption about the ownership proof. That is precisely the extra behavioral context a mutation tool needs.

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?

Four short sentences, each carrying distinct information: authorization scope, mutation effect, key-retention warning, and a non-obvious negative constraint. The permission requirement is front-loaded and there is no filler.

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 an output schema present, return values need no explanation, and the description covers everything else an agent needs: who may call it, what it destroys, what must be saved, and what it does not require. Nothing material is missing for a two-parameter destructive operation.

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 description coverage is 100% for both parameters, so the schema already documents 'domain' format and the 'awm_key_...' key format. The description only refers to 'the API key' generically and adds no format, length, or source details beyond the schema. Baseline 3 is appropriate when the schema does the heavy lifting.

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 — replace the API key — plus the immediate consequence, invalidating all existing browser owner sessions. This operation is unmistakably distinct from siblings like verify_domain (issues keys) or register_domain (creates domains). An agent can identify exactly what this tool does without opening the 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?

'Owner only' establishes a clear precondition, and 'Does not require changing the existing ownership proof' clarifies an expected side-effect the caller might otherwise assume. However, it never states when to rotate versus other paths (e.g., re-running verify_domain) or any irreversible-consequence warning beyond the session invalidation. Usage is implied rather than explicitly routed.

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