expense_breakdown

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only states the function and omits whether the operation is read-only, how aggregation works, any limitations, or output format specifics (though an output schema exists). No side effects or permission requirements are mentioned.

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, clear sentence that concisely conveys the core purpose without unrelated detail. It is front-loaded with the action and resource, making it easy to parse.

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?

The tool has moderate complexity (6 parameters, 2 required) but the schema fully documents parameters and an output schema exists. The description is adequate for understanding the primary function, yet it does not explain the relationship between group_by and breakdown or provide examples. The schema compensates, making this sufficient but not comprehensive.

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?

The input schema provides descriptions for all 6 parameters (100% coverage), meeting the baseline of 3. The description adds only a vague reference to 'columns or time units' without enriching parameter meaning or clarifying interactions between group_by and breakdown beyond schema details.

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 clearly states the tool's function using a specific verb ('Summarize and breakdown') and resource ('expenses'), and specifies the grouping dimensions ('by columns or time units') and date range scope. This distinguishes it from siblings like list_expenses (raw listing) and expense_summary (overall summary), which likely lack the breakdown focus.

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 implies the tool is used for generating grouped expense summaries within a date range, but it does not explicitly state when to use it over alternatives or provide exclusions. There is no comparative guidance, leaving usage to inference.

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