Creates a new category group in a YNAB budget to organize categories. Provide a name and optional budget ID.
Creates a new category group (a section that categories live under) in a budget.
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | The name of the new category group (max 50 characters). | |
| budget_id | No | The budget ID, or 'last-used' for the most recently used budget. | last-used |
Changes observed during successful MCP inspections.
v1.9.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden. It does not disclose side effects, required permissions, error conditions, or what happens on duplicate names; it only says it creates a group in a budget.
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 that defines the resource inline and wastes no words. It is appropriately sized for a simple create operation.
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 tool with a fully documented schema and no output schema, the description is largely sufficient; an agent can call it with just a name and an optional budget ID. It could still be improved with basic usage context, but nothing critical is missing for correct invocation.
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 two parameters (name, budget_id) are already fully documented in the schema. The description adds no parameter-specific detail beyond what the schema provides, meriting the baseline 3.
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 ('Creates') and resource ('new category group'), and the parenthetical definition ('a section that categories live under') helps distinguish it from a plain category. However, it does not explicitly name or differentiate itself from sibling tools like create_category.
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 offers no when-to-use guidance, no prerequisites, and no alternatives. It simply asserts the action, leaving the agent to infer that this is the tool for creating category groups rather than categories.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.