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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so safety is covered. The description adds genuinely useful behavioral content beyond that: it discloses the lookback window (last 30 days) and the exact return payload (bidding type, targets, conversions, clicks, cost), which matters since there is no output schema.

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 tight sentences: the first states what is returned, the second states when to call it. Nothing is redundant and the key content is front-loaded.

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 simple two-parameter read tool with rich annotations and no output schema, describing the return contents and the pre-change workflow is nearly enough. The remaining gap is parameter meaning, which the description leaves to the schema, and the schema is silent.

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 neither required parameter (customer_id, campaign_id) is documented anywhere. The phrase "for one campaign" loosely implies campaign_id, but customer_id — the account scoping parameter — is never explained, so the description does not 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?

The description names the specific resource (bidding strategy for one campaign) and enumerates the fields it covers (type, target CPA/ROAS/CPC ceiling) plus associated metrics. It is clearly a read of current state, which implicitly separates it from the write sibling ads_set_bidding_strategy, though it never names that sibling directly.

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?

"Check this before proposing a strategy change" gives explicit decision context and ties the tool to a concrete workflow (inspect before mutating strategy). It does not state any when-not-to-use case or name an alternative tool explicitly, so it stops short of a 5.

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