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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds nothing beyond that: it does not say how the period is aggregated, whether the range is inclusive, or how income and expenses are compared, leaving the behavioral picture essentially empty.

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?

A single front-loaded sentence with no filler or repetition. It is efficient, though its brevity stems partly from under-specification rather than disciplined editing.

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 two-parameter, read-only tool with full schema coverage the requirements are modest, and the description conveys the gist of what is returned. With no output schema, though, it should say more about the shape of the "overview" (totals only, per-category, per-period), which it does not.

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 100% and both startDate/endDate are documented in the schema as YYYY-MM-DD. The description adds no format, boundary, or default information beyond the schema, which matches the baseline 3 for fully documented 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?

States a specific verb and resource ("Get income vs expenses balance overview"), so an agent can tell it apart from tools like get_top_merchants or search_expenses. However, it gives no hint of how it differs from near-neighbours such as get_income_summary or get_spending_summary, and "overview" leaves the granularity unspecified.

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 when-to-use guidance, no exclusions, and no named alternative among the 15 sibling tools. The income-vs-expenses framing only weakly implies the scenario (a combined balance view rather than a single-sided summary).

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