Category balances for a month

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

Annotations already declare readOnly/idempotent/openWorld, but the description adds real behavioral context beyond them: amounts are in currency units, activity is negative for spending, and hidden/internal or empty categories are silently excluded unless include_empty is set. That sign convention and default-filter disclosure materially affect how an agent interprets results.

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?

Four short sentences, front-loaded with the resource and its three metrics, then filtering rules, then the sibling hand-off. No filler and nothing repeated from the schema.

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?

With an output schema present and rich annotations, the description does not need to explain return shape; it still covers units, sign convention, default exclusions and the alternative tool. Nothing needed to invoke or interpret it correctly is missing.

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%, so the schema already documents month, plan_id and include_empty, making 3 the baseline. The description reinforces include_empty's effect and the currency/sign semantics of returned amounts but adds no new parameter syntax or format detail beyond the schema.

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 states exactly what is returned (budgeted, spent/activity, available/balance per category) and scopes it to a month. It also names the sibling get_budget_vs_actual and the distinction that selects it, so an agent can tell the two apart without opening either schema.

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?

It explicitly routes the agent elsewhere ('Use get_budget_vs_actual for the share of each budget consumed') and discloses the default filtering behavior (hidden/internal categories and zero-amount categories omitted unless include_empty). It stops short of stating when this tool is the right first choice versus other summary tools like get_monthly_summary or get_spending_trends.

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