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

With readOnlyHint already provided by annotations, the description adds substantial behavioral context: no invented fatigue, winning status, product promises or sample thresholds. It also states that a source is a control candidate not a validated winner, that no asset is produced or campaign prepared, and that answer mode returns a report the agent writes from. This is rich beyond the structured annotations.

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 dense but every sentence carries meaningful operational or safety constraints. It is front-loaded with the precondition and exclusions, though the paragraph could be easier to scan with clearer structure. It avoids redundancy and stays reasonably sized for a tool with this many behavioral rules.

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?

The description is complete enough for a read-only review tool: it explains the evidence scope, what is included, what is not produced, and how answer vs evidence mode affects output. There is no output schema, but the description indicates that the answer mode returns a report the agent writes the reply from. Pagination behavior and language semantics remain delegated to the schema and are minor gaps.

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?

The description fully explains the focus modes (copy_test, market_transfer) and gives strong guidance on responseMode evidence vs answer. Schema description coverage is 75%, and the schema documents adIds and destination well. Language, limit/offset and accountIds are not elaborated in the description, so it is not a 5.

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 and resource: review exact selected ad evidence after certain prior analyses. It also clearly excludes creation ('No asset produced or campaign prepared') and invented conclusions. It does not explicitly distinguish itself from close siblings such as creative_insights or creative_market_evidence, which keeps it at 4 rather than 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?

It specifies when to use the tool: after creative-map, creative-fatigue, creative-roadmap or market-test. It also explains when to use each focus mode and when to choose evidence vs answer. It does not explicitly say when to prefer sibling tools instead, but the internal mode guidance is clear.

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