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

Annotations already declare the mutation profile (readOnlyHint=false, destructiveHint=false, idempotentHint=false, openWorldHint=true), so the safety picture is covered structurally. The description adds nothing behavioral – notably it omits the preview/confirm two-step flow (the confirm param's default-false dry-run), which is the most important behavior for this tool. It also says nothing about auth or side effects.

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?

Two short sentences, front-loaded with the core action, no padding. The second sentence is relevant thematic advice rather than filler, though it is generic enough that it could be tightened.

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 5-parameter mutation tool with 20% schema coverage and no output schema, the description leaves too much unexplained – especially the required identifiers and the confirm-dry-run mechanism. An agent could invoke it but lacks the context to use it safely or correctly without reading 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 coverage is only 20% (just the confirm param). The description mentions campaign context but never names or explains customer_id, campaign_id, name, or cpc_bid_major, and does not tie the confirm preview behavior into prose. It fails to compensate for the coverage gap.

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 clear verb+resource: 'Create an ad group inside a campaign.' An agent can distinguish it from sibling write tools like ads_create_campaign and ads_create_ad, though the description never explicitly contrasts them. The scope (ad group nested in a campaign) is conveyed.

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?

There is no guidance on when to use this vs alternatives (ads_create_campaign, ads_add_keywords) or on prerequisites like an existing campaign_id. The second sentence is bidding/keyword-grouping advice, not usage selection guidance.

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