list_control_account_usages

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

The readOnlyHint annotation already signals a safe read operation. The descripetion adds context by specifying the aggregate nature, the plural control-account scope, and the daily metrics, which is useful behavior beyond the annotation. It does not disclose pagination behavior or default filter behavior, but the annotation lowers the burdden.

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 a single, tightly written sentence that leads with the action and resource, then states the return metrics. Every word adds value, and it is not padeded.

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?

While the description communicates the core purpose and return contents, with 9 optional filter parameters and no output schema there is no explanation of default behavior (e.g., whether filters are required, how pagination works, or what happens when no filters are provided). The schema covers parameter details, but the holistic context for an agent deciding on invocation is incomplete.

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 all nine parameters are already well documented with descriptions. The description does not add param-specific meaning, but that's acceptable because the schema carries the load. The mention of 'daily metrics' hints at the date range parameters, but does not go further.

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 uses a specific verb ('List') and a specific resource ('usage data across Control Accounts'), and enumerates the actual metrics returned (storage, egress, ingress, API calls). It clearly distinguishes from siblings like list_usages or get_control_account_usage by scoping to control-account usage and aggregating daily metrics.

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 such as list_usages, get_control_account_usage, or list_sub_account_buckets. The description only states what the tool does, not under which circumstances it should be selected.

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