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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered without the description. The description adds no behavioral context beyond the bare purpose and does not contradict the annotations, making 3 the appropriate ceiling.

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?

A single tight sentence with no padding, and the core purpose is front-loaded. Its problem is under-specification rather than verbosity.

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?

Output schema exists so return values need no explanation, and the rich schema carries the constraints (60-day range, 1-3 breakdowns, pagination). However, for a tool this complex with a confusingly similar sibling, the description leaves the agent without enough to choose or scope it 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 filters, breakdowns, date_range, and workspace_id. The description only gestures at 'metrics' and 'breakdown field', adding no syntax or constraint detail beyond the structured fields, which lands at the baseline 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?

The description names a specific verb and resource: it retrieves breakdown data of given metrics by a given breakdown field. An agent can understand the operation, but it never differentiates itself from near-identical siblings like analytics_aggregated_data, analytics_chart_data, or especially insights_breakdown_data.

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?

There is no guidance on when to use this tool versus alternatives. Given the sibling set contains both analytics_breakdown_data and insights_breakdown_data plus aggregated/chart variants, the absence of any routing guidance is a real gap.

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