account_ledger

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

With no annotations, the description carries the full burden. It discloses the default active-sub-account filtering and enumerates valid account_status values, which is valuable behavioral context. It also implies a read-only nature. It does not mention pagination or output format, but the output schema likely covers return structure. This exceeds a baseline given the absence of 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?

The description is three sentences, front-loaded with the core purpose and efficiently organized. Every sentence adds value: the first states the main function, the second clarifies output (usage charges by date range), and the third explains default and alternate behaviors. No unnecessary words.

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 the presence of an output schema, return values are covered elsewhere. The description provides essential operational context: default filtering, date-range usage, and account_status options. For a read-only query tool with no required parameters, this is largely complete. Minor gaps include lack of mention of account_ids and any permissions, but these are acceptable given the simplicity.

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%, so the description must compensate. It clarifies account_status values and implies that start_date and end_date form a date range. However, the account_ids parameter is not mentioned at all. With four parameters, the coverage is partial and leaves one parameter entirely ambiguous, so the description adds some value but is not fully compensatory.

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 'Get' and resource 'billing/ledger data across sub-accounts', clearly indicating the tool's function. It explicitly states it shows usage charges for a date range, which adds clarity. While it doesn't explicitly contrast with siblings like account_summary, the resource focus is distinct enough.

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 provides clear context on default behavior (queries active sub-accounts) and how to adjust via account_status. However, it does not mention when to use this tool over alternatives like account_summary or reports_series, nor does it provide any exclusion criteria. Usage guidance is implied rather than explicit.

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