expense_summary

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

Since no annotations are provided, the description must disclose behavioral traits itself. It only mentions chart generation but does not state whether the operation is read-only, whether it has side effects (e.g., saving files), or how the chart is returned. It also omits fallback behavior when no grouping is given, leaving important operational details undisclosed.

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 extremely concise: two sentences, with the core purpose in the first and a practical recommendation in the second. It contains no fluff or repetition, making it maximally efficient and easily scannable.

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 (which likely covers return values) and full schema coverage for parameters, the description is sufficiently comprehensive for the tool's moderate complexity. It lacks detail on chart specifics or edge cases, but the essential purpose and key usage note are present, so it is not 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?

The schema already documents all six parameters (100% coverage), so the baseline is 3. The description adds non-redundant value by framing 'period' and 'group_by' as grouping dimensions and recommending that at least one be used. This helps the agent understand the intended relationship and prioritization among the optional parameters.

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 specifies a clear verb ('Generate'), a resource ('expense summary'), and distinguishing attributes ('analytical', 'rich Matplotlib chart'). This positions it as a distinct analytical tool compared to siblings like list_expenses (which lists) and expense_breakdown (which breaks down), leaving no ambiguity about its core function.

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 recommendation to use at least one grouping dimension ('period' or 'group_by') provides clear, actionable guidance on how to invoke the tool effectively. However, it does not explicitly contrast the tool with alternatives like expense_breakdown or list_expenses, so an agent might not know when this summary/chart tool is preferable over those siblings.

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