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

Annotations already declare destructiveHint=true and idempotentHint=true; the description earns credit by explaining the concrete destructive outcome (bid_modifier=0.0 excludes the device entirely) and the valid 0.0–10.0 range, which an agent cannot infer from the hints alone. It does not cover permission or auth prerequisites.

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 purpose sentence followed by actionable usage and a compact Args/Returns block. The 'Returns' section restates a value already covered by the output schema, and 'Bid adjustment as a multiplier' mildly duplicates the scale table, but there is no real bloat.

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 4-required-parameter mutation tool with annotations and an output schema, everything an agent needs to call it correctly is present: formats, enum values, numeric range, and the meaning of edge values. Return details are already covered by the output schema.

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 compensate and does: each of the four parameters is documented, including the 'numbers only, no hyphens' format for customer_id, the enumerated device types, and the full multiplier scale with worked examples (0.5 = -50%, 1.5 = +50%).

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 (sets), resource (bid adjustment), and scope (a specific device type on a campaign). This clearly separates it from nearby siblings like set_campaign_status, update_campaign, and set_geo_targets.

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 second paragraph gives concrete usage context: increase or decrease bids for Mobile/Desktop/Tablet, or exclude a device with bid_modifier=0. It stops short of naming explicit alternatives or when-not-to-use conditions, so it is clear context rather than full routing guidance.

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