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

Annotations already establish readOnly, idempotent, non-destructive, closed-world, so the safety burden is lifted. The description adds genuine behavioral context beyond them: aggregation semantics when resource_id is omitted and hard ownership/account constraints per resource type, which an agent cannot derive from the 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?

Three short sentences, front-loaded with the output and scope, followed by the aggregation rule and the permission constraint. Nothing is padded or redundant.

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?

With a full output schema and complete annotation set, the description need not explain return values or safety. It covers scope, aggregation, and access restrictions adequately; only the lack of sibling differentiation (breakdown vs views) leaves a minor gap for tool selection.

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 coverage is 100%, so the aggregation meaning of omitting resource_id is already documented in the schema and is essentially repeated here. The description still adds meaning the schema lacks by mapping resource_type values to account eligibility (creator vs agency), which informs parameter choice.

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 — 'Return page views and unique visitors' — and enumerates the five resource types it applies to. It is clear without opening the schema, but it never names the sibling analytics_get_breakdown, so the agent must infer from the title alone which analytics tool to pick.

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 gives actionable context: omit resource_id to aggregate, and resource type is gated by account kind (link in bio creator-only, roster/deck agency-only). That tells the agent when the call is valid, though it does not contrast itself against analytics_get_breakdown or state what to do if a type is not available to the caller.

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