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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered and not contradicted. The field enumeration adds value by describing the read surface, but nothing is said about behavior for unset targeting types, whether negative lists come back as IDs or expanded, or any scoping limits despite openWorldHint=true.

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 sentences, purpose first and usage instruction second, with no padding. The component list is dense but each item is necessary information about what is included.

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 read-only aggregator with no output schema, enumerating the returned components is exactly the right completeness move. The remaining gap is the undocumented campaign_id and no note on campaigns with no targeting configured.

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 50%: 'account' is described, 'campaign_id' is not. The description never mentions either parameter and only loosely implies campaign_id via 'one campaign', giving no guidance on resolving the account/campaign pair.

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 description names a specific resource (one campaign's targeting) and enumerates the exact components returned: locations/radius, languages, ad schedule, device bid adjustments, audiences, negative keyword lists and campaign negatives. That distinguishes it from setters like google_ads_set_ad_schedule or google_ads_set_device_bids, though it never states a verb such as 'retrieve'.

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?

'Use before changing targeting' supplies a concrete workflow trigger telling an agent when to reach for this tool. It stops short of naming the write tools (set_ad_schedule, set_device_bids, add_audiences) that would follow, so routing is implied rather than explicit.

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