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

Goes well beyond the annotations, which only state that this is a destructive, non-idempotent, non-readonly write. The description discloses that a bare 'replace' would otherwise silently delete the rest of the list and that the merge happens here, that switching to a maximize strategy drops the manual bid, that unpassed bid settings and audience multipliers are preserved, and that confirm=false returns a dry run.

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?

The purpose is front-loaded and the long middle is dense, concrete parameter semantics rather than filler, with a worked good/bad hint example. It is more verbose than most definitions, but nearly every clause carries an actionable constraint.

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?

An output schema exists, so return values need no explanation, and the annotations already cover the safety profile. For a 9-parameter destructive mutation the description supplies the merge/preservation strategy, bid validation and dry-run behavior an agent needs to call it correctly; only the multi-account `account` selector is unaddressed.

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 0% and there are no enums in the schema, so the description carries the full burden — and it does so for hints_mode (add/replace/remove/clear), strategy (fixed_bid | maximize_clicks | maximize_conversions), max_bid (account currency, sanity ceiling), allow_high_bid and confirm. The `account` parameter is never explained and `ad_group_id` is only implied, which keeps this from a 5.

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?

Opens with a specific verb and resource ('Changes the name, bid, bid strategy or context hints of an existing ChatGPT Ads ad group'), naming the mutable fields up front. It is clearly distinguishable from create_chatgpt_ads_ad_group, update_chatgpt_ads_campaign and update_chatgpt_ads_ad in the crowded sibling list 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?

Gives real routing guidance: hints_mode 'add' is stated as the default and the safe one, 'customers in California' is explicitly redirected to country targeting, and allow_high_bid is named as the escape hatch for a deliberate high bid. It stops short of explicitly naming a sibling tool to use instead (e.g. the geo-targeting tool), so it is clear context rather than full when/when-not routing.

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