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

Annotations already mark readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context: it lists the exact metrics returned, states that the response is paginated with totalElements/totalPages/data array, and clarifies channel filtering. This goes beyond the annotations without contradicting them.

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 longer than typical but well-structured with clear labels (USE FOR, NOT FOR, CHANNELS, METRICS, pagination note). It is front-loaded with purpose and uses a scannable format. Every section provides distinct value; while slightly verbose, no sentence is wasteful. Score 4 rather than 5 due to the length.

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 six optional parameters and no output schema, the description compensates by detailing the metrics available, channel options, pagination behavior, and usage boundaries. It fully equips an agent to call the tool correctly without needing additional documentation. The absence of prerequisites or rate limits is acceptable for a read-only 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?

The input schema has 100% description coverage for all six parameters, each with detailed examples (e.g., page, size, sort, date formats). The tool description adds no additional parameter-level semantics beyond what the schema already provides. Per the rubric, when schema coverage is high, baseline is 3, and the description does not elevate it.

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 clear verb ('get'/'list') and resource ('account list performance'), then lists the exact metrics and scope ('account list information with engagement metrics and statistics'). It distinguishes itself from siblings by naming alternatives in the NOT FOR section (e.g., 'use experiment_performance_stats'), so an agent can select it correctly without opening other tools.

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 explicitly provides USE FOR and NOT FOR sections, naming specific sibling tools for excluded cases (e.g., 'Campaign-level details (use experiment_performance_stats)'). This gives direct guidance on when to use this tool versus alternatives, with no ambiguity.

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