google_ads_bid_adjustments_update

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

With no annotations, the description fully discloses behavioral traits: it states it's a mutating FieldMask-based partial update, reversible, and specifies the valid range and error handling for out-of-range values. This covers safety and 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?

The description is three sentences, each serving a clear purpose: action, behavioral details, and constraint/alternative. It is front-loaded with the primary function and avoids unnecessary words.

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?

Given the tool's simplicity (4 parameters, no output schema), the description covers all necessary aspects: parameter usage, constraints, alternative tool, and update behavior. No additional context is needed.

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 100% with parameter descriptions, so baseline is 3. The description adds value by explaining how to obtain campaign_id and criterion_id, the meaning of bid_modifier values (e.g., 0.1 = -90%), and that customer_id is optional with fallback. This provides useful context beyond the schema.

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 clearly states the tool updates the bid_modifier of a single campaign_criterion and returns the resource_name. It distinguishes from the sibling tool google_ads_device_targeting_set for toggling devices with bid_modifier 0.0, which is explicitly rejected here.

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?

The description provides explicit when-to-use context: it's for updating bid_modifier only, and when to use the alternative google_ads_device_targeting_set for device on/off toggling. It also mentions that the update is reversible and that the range is enforced.

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