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

Annotations already mark this as a non-destructive, non-idempotent write (readOnlyHint=false, destructiveHint=false, idempotentHint=false). The description adds meaningful behavior beyond that: the mandatory three-value constraint, that values are percent bid adjustments with 0 meaning no change, and the preview/apply semantics of confirm.

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 that lead with the action and the mandatory constraint, then the value semantics and confirm modes. No filler, though the parenthetical formatting is slightly compressed.

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?

With an output schema covering return values, the description only needs to cover invocation concerns. It handles the mutation behavior, the required-together constraint, and preview vs apply, leaving only identifier parameters unaddressed, which is a minor gap for a 7-param tool.

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 0%, so the description must carry parameter meaning. It does well for the device values (percent adjustments, 0=no change, send all three together) and for confirm, but account_id, campaign_id, and customer_id are never explained even though two are required. Partial compensation warrants a 3.

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 (adds) and resource (device bid adjustments for Microsoft), which is enough to distinguish it from siblings like add_microsoft_demographic_target or manage_device_targeting. It does not explicitly name an alternative sibling, so it stops short of a 5.

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?

Gives concrete usage context: all three device values must be sent together (a Microsoft requirement) and confirm=false previews while confirm=true applies. It does not compare against the closest sibling manage_device_targeting, so it provides clear context but no explicit alternatives.

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