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

Annotations already cover the safety profile with readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the description adds useful behavioral detail beyond them: per-currency series, 'never summed across' semantics, and exclusion of transfer legs. It does not contradict any annotation.

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 contain only relevant, substantive information. The main behavior is front-loaded and every clause adds detail, with no filler or redundant restatement of the tool name.

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 report with an output schema, the description captures the core scope, aggregation rule, and transfer-leg exclusion. The only real gap is the behavior of an omitted optional currency parameter, which is minor given the tool's low complexity.

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 for the parameters. It does clarify that 'months' controls the trailing window and 'currency' drives the series grouping, but it leaves unspecified currency format, default behavior when currency is omitted, and how the two parameters interact.

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?

Description clearly states the tool's output: spent and received amounts per calendar month for a trailing window, with one series per currency and no cross-currency summation. It also distinguishes itself by surfacing 'received' rather than only spending and by explicitly excluding transfer legs.

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?

No guidance is given about when to use this tool versus related reporting siblings such as spending_summary, budget_status, chart, or net_worth. The intended use is only implicit in the metric definition; no alternatives or exclusions are mentioned.

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