Category groups — Summary by month

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

Annotations already declare readOnly/non-destructive, but the description adds substantial non-obvious context: hidden categories are included by default and why (dropping the credit-card payment group), milliunits convention, and the cost model (one request per month, 36-month cap). This is behavior an agent cannot get from the schema or annotations.

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?

Front-loads a [READ] tag and the core purpose, then layers format, defaults, cost. Every sentence earns its place with no filler; density is high but not padded.

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?

An output schema exists so return values needn't be described; given the tool's complexity, the description covers inputs, defaults, units, cost limits and sibling relationship. Nothing essential to a correct call 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?

With 0% schema description coverage the description must carry parameters, and it does for three of four: from_month/to_month accept 'YYYY-MM', ISO date, or 'current', to_month defaults to current month, and include_hidden defaults true with a rationale. Only plan_id is left unexplained.

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?

State a precise verb+resource: per-group, per-month totals of budgeted, activity and balance. It explicitly contrasts with a category-level view ('a group view is small enough to read whole where a category view is not'), so an agent can distinguish it from sibling aggregation tools.

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?

Names the question class it serves ('is this budget healthy' at group level), states the default for to_month, and warns to check overview_request_budget before a long range. It routes the agent toward the right scenario and away from costly misuse.

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