monthly_summary

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

The readOnlyHint annotation already declares this as a read-only operation, and the description ('showing') is consistent. The description adds that it aggregates multiple months and highlights trends, which is useful functional context, but it does not disclose any additional behavioral details beyond the annotation. With annotations covering the safety profile, a 3 is appropriate.

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?

Two sentences with no fluff. The first sentence states the core functionality, the second gives a use case. All information is relevant and front-loaded, making it easy to parse quickly.

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?

For a simple read-only tool with one optional parameter and no output schema, the description covers the key aspects: what metrics are shown, the multi-month scope, and the intended use case. It could be slightly more explicit about the output format (e.g., per-month breakdown), but given the tool's simplicity, this is a minor gap.

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% because the single parameter 'months' has a description ('Number of months to show (default 3)'). The tool description reinforces the concept of multiple months but adds no new semantics about the parameter. Since the schema fully documents the parameter, the baseline 3 applies.

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 a specific verb ('showing') and resource ('monthly financial summary'), and lists the specific metrics (income, expenses, savings, savings rate). The phrase 'across multiple months' distinguishes it from month-specific siblings like get_budget_summary or budget_vs_actual, making the tool's scope unambiguous.

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 gives a clear usage context ('Great for seeing trends in your overall financial health'), implying when to use it. However, it does not explicitly name alternative tools or state when NOT to use it, leaving some inference required for an agent comparing siblings.

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