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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds only that results can span one or all ad accounts, which explains why the account param is optional; it says nothing about date-range defaults, pagination behaviour, or what the fatigue/signals views actually return.

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 front-loaded sentence with no filler. It is efficient, though its brevity leaves the tool under-specified rather than truly concise.

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 an 8-parameter analytics tool with zero schema descriptions and no output schema, the description is not complete enough: date-window semantics, pagination, and per-view return shapes are all unaddressed. An agent could select the tool but would likely guess at parameter semantics.

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 0% across 8 parameters, so the description carries the full burden and fails to meet it. The only mapping it provides is the view vocabulary, which is already explicit in the schema enum; nothing explains from/to versus days, the 1-100 limit cap, or the cursor contract.

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 the resource (provider ad metrics) and enumerates the breakdown dimensions (day, creative, fatigue, country, audience, signal) that map to the view enum, so an agent knows what it retrieves. It does not distinguish this from the sibling ads_performance_get, leaving the exact division of labour unclear.

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 when-to-use guidance at all: nothing says how this differs from ads_performance_get, when a breakdown is preferable to the performance endpoint, or what account scoping means in practice. The agent must infer usage from the name alone.

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