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

Annotations already declare readOnlyHint, openWorldHint=false, and idempotentHint, so safety/idempotency are covered. The description adds genuine value beyond that: a detailed disclosure of returned content, the 'source of truth' role relative to generate_campaign_draft, and expectations about surfacing/validating output. It stops short of noting performance, pagination, or failure modes for a missing draftId.

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?

Front-loaded with the return contract, then usage and downstream guidance. The parenthetical enumerations of settings and per-ad-group fields are long but directly informative rather than filler, so the size is justified, though it could be trimmed slightly.

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?

There is no output schema, so the description rightly carries the burden of explaining return contents, which it does thoroughly, plus it clarifies the relationship to generate_campaign_draft and publish_campaign_to_google_ads. The only real gap is not clarifying the draftId parameter.

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?

The single draftId parameter has 0% schema description coverage and the description never explains it, so no compensation occurs. However, with only one self-evidently named ID parameter, 3 is appropriate as the minimum-viable baseline; it adds nothing beyond the schema's integer/exclusiveMinimum typing.

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 (inspect/return contents) and resource (campaign draft), then enumerates exactly what is returned: campaign-level settings, per-ad-group keywords with volume/bid/competition, and generated headlines/descriptions. It clearly distinguishes itself from sibling list_campaign_drafts and generate_campaign_draft by being the 'source of truth' for full draft contents.

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?

Explicitly states when to use it ('BEFORE publish_campaign_to_google_ads so the user can see what they're about to create') and contrasts it with the alternative ('The draft summary returned by generate_campaign_draft is intentionally brief'). It even prescribes downstream behavior (show headlines + sample keywords, flag off-target ad groups), leaving little to inference.

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