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mcp-ynab

by alexfu

updateCategoryGroup

Update the name of an existing category group in your YNAB budget by specifying the plan, group ID, and new name.

Instructions

Update a category group

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
plan_idYesThe id of the plan. "last-used" can be used to specify the last used plan and "default" can be used if default plan selection is enabled (see: https://api.ynab.com/#oauth-default-plan).
category_groupYes
category_group_idYesThe id of the category group

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
dataYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

C2/5.0
Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only implies mutation via "update" but does not state whether the update is partial or full, whether existing values are replaced, what permissions are needed, or what side effects occur.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness2/5

Is the description appropriately sized, front-loaded, and free of redundancy?

While the description is short and free of filler, it is under-specified rather than truly concise. The single sentence merely restates the tool name and does not earn its place by adding operational value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With three required parameters, one nested object, and no annotations, the description is too thin to be complete. It leaves out update semantics, required field behavior, and context about where category_group_id comes from, even though an output schema exists.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 67%, with plan_id and the category_group.name property documented, but category_group_id is only described as "The id of the category group." The description adds no meaning beyond the schema and does not help an agent understand how to obtain or use the IDs correctly.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose2/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description "Update a category group" is essentially a restatement of the tool name and provides no distinguishing scope, fields, or behavior. It does not differentiate from sibling tools like updateCategory, updateMonthCategory, or createCategoryGroup, so an agent gains little clarity beyond the name itself.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives no guidance on when to use this tool versus alternatives. It does not mention prerequisites such as needing an existing category_group_id, nor does it point to createCategoryGroup for initial creation or updateCategory for category-level updates.

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