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

Beyond the annotations (destructiveHint=false), it discloses that the campaign defaults to PAUSED, that budget is newly created, that unsupported channels return {error: unsupported_channel, hint}, that PMax final-URL-expansion cannot be disabled via API, and that campaigns are created without EU political advertising. These are exactly the side effects and limitations an agent 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?

Every sentence carries operational information and the critical facts (purpose, default PAUSED status) are front-loaded. It is dense and somewhat run-on in the network/PMax paragraph, which slightly hurts scanability, but nothing is 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?

For an 11-parameter mutation tool with an output schema present, the description covers the full lifecycle: creation semantics, default state, per-parameter constraints, rejection behavior, and required follow-up calls for PMax. An agent can call this correctly without consulting anything else.

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 0%, so the description must carry all parameter meaning — and it does: enumerated channel_type values with SHOPPING exclusion, bidding_strategy options with the PMax constraint, the fact that target_cpa_eur/target_roas are ignored outside their matching strategies, defaults for the three network flags, and the PMax caveat that networks don't apply.

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 first sentence states a specific verb and resource ('Neue Kampagne anlegen') and adds the important detail that a campaign-owned budget is created with it. It is clearly distinguishable from sibling tools like ads_update_campaign_settings or ads_create_ad_group.

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?

It gives concrete conditional guidance: SHOPPING is rejected before the API call, PMax requires calling ads_create_asset_group + ads_add_asset_group_signal afterwards, and workspace may be omitted when only one exists. It stops short of explicitly naming when to use update vs. create alternatives, but the creation context is unambiguous.

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