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

Annotations already declare destructiveHint=true, idempotentHint=false, and openWorldHint=true, so the safety profile is covered. The description usefully adds that REMOVED is permanent and that raising the bid raises cost-per-click, which is real behavioral context beyond the annotations, but it omits idempotency, permissions, and rate-limit context.

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?

Three short, front-loaded sentences with the core action first. The middle sentence about bid cost is mildly self-evident but serves as a spend caution, so it earns its place; no true waste.

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 6-parameter mutation with a rich parameter-level schema and annotations covering safety, the description covers the purpose and the key permanence/spend warnings. No output schema exists, so return values need not be explained. It is essentially complete, though validateOnly/extraFields usage is left entirely to the schema.

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 83%, so the schema already documents cpcBid, status, customerId, extraFields, and validateOnly in depth. The description only names 'status' and 'default max CPC' at a high level, adding little beyond what the schema provides; baseline 3 applies.

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+resource: changing an ad group's status and/or default max CPC. An agent can distinguish it from siblings like update_campaign or update_keyword by the ad-group resource. It stops short of explicitly naming which sibling to use for related tasks, so it is not a 5.

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 gives no when-to-use vs alternatives guidance, no prerequisites, and no sibling routing (e.g., vs update_ad_status or update_campaign_status). The 'REMOVED is permanent' note is a caution, not usage guidance. Nothing tells the agent the conditions under which to pick this tool.

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