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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safe read nature is known. The description adds useful behavioral context: the exact fields returned, UTC ISO-8601 timestamp format, and the rule that Sponsored Display supports only ASIN Targets and negative ASIN Targets. It does not cover rate limits or authentication, but with annotations that is acceptable.

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 front-loaded with what the tool returns, followed by downstream usage and specific constraints. Four sentences, each earning its place with no redundant information. The structure is efficient and easy to parse.

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 existence of an output schema and the read-only annotations, the description provides complete context: it explains the returned fields, how results feed into other tools, and domain-specific targeting constraints. An agent has everything needed to invoke the tool correctly.

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 100%, so the schema already documents all six parameters thoroughly. The description does not add any parameter-specific meaning beyond what the schema provides; the mention of campaign.campaignType refers to output fields, not input parameters. Baseline 3 is appropriate.

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 states a specific verb (Returns) and resource (advertising ad groups), and enumerates the exact fields returned including IDs, state, bid, campaign details, and timestamps. It does not explicitly differentiate from sibling query tools like query_advertising_campaigns, but the scope is clear enough for an agent to distinguish it.

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 gives clear context for when to use the results: they can proceed to AD_AD_GROUP_CHANGE, AD_AD_CREATE, or AD_TARGETING_CREATE. It also provides a domain constraint for choosing targeting inputs based on campaign.campaignType. However, it does not name alternative query tools or state when not to use this tool.

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