YNAB MCP Server

List Categories

list_categories

Read-onlyIdempotent

Retrieve YNAB category groups and categories with current-month budgets, activity, balances, and hidden/deleted/internal flags to review budget status.

Instructions

List groups/categories with current-month dollar budgets, activity and balances. Includes hidden/deleted/internal flags. Use get_month for other months or search_categories for names.

Input Schema

Name	Required	Description
`budgetId`	No
`freshness`	No	fresh (default) reads YNAB. cached uses a session-isolated 30-second cache; complete means its reported coverage, which expands for older requested dates. Reports freshness; caller delta cursors bypass retention.
`projection`	No	Output fields: full (default) or lean IDs, values and essential status/link fields. Splits retain child IDs and amounts.
`includeFreshness`	No	Return an envelope with freshness/coverage metadata even on a fresh read.
`lastKnowledgeOfServer`	No	Delta cursor; returns { category_groups, server_knowledge }.

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed7 schema fields changedv6.1.0Oct 25, 2026

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

removedInput schema / properties / budgetId / description

Removed value: -"Budget ID (uses default if not provided)"

addedInput schema / properties / freshness

Added value: +{
+  "description": "fresh (default) reads YNAB. cached uses a session-isolated 30-second cache; complete means its reported coverage, which expands for older requested dates. Reports freshness; caller delta cursors bypass retention.",
+  "enum": [
+    "fresh",
+    "cached"
+  ],
+  "type": "string"
+}

addedInput schema / properties / includeFreshness

Added value: +{
+  "description": "Return an envelope with freshness/coverage metadata even on a fresh read.",
+  "type": "boolean"
+}

changedInput schema / properties / lastKnowledgeOfServer / description

Previous value: -"Delta request server knowledge. When provided, returns { category_groups, server_knowledge }."New value: +"Delta cursor; returns { category_groups, server_knowledge }."

addedInput schema / properties / projection

Added value: +{
+  "description": "Output fields: full (default) or lean IDs, values and essential status/link fields. Splits retain child IDs and amounts.",
+  "enum": [
+    "lean",
+    "full"
+  ],
+  "type": "string"
+}

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Changed1 schema field changedv5.4.0Sep 15, 2026
- removedOutput schema / properties / result / description
```
Removed value: -"Structured result returned by List Categories."
```
Addedv5.2.0Aug 29, 2026
Removedv5.1.1Jul 21, 2026
First observedv2.0.0May 28, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare the full safety profile (readOnly, idempotent, non-destructive, closed-world), so the description only needs to add behavior beyond that. It does: 'Includes hidden/deleted/internal flags' tells the agent that archived/deleted categories are present in results by default, a non-obvious trait that affects filtering downstream. It does not touch freshness/caching or delta-cursor behavior, but the schema covers those, so this is short of a 5 rather than a gap.

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

Conciseness5/5

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

Two sentences, zero filler, and the result-shape statement is front-loaded before the disambiguation clause. Every sentence earns its place and the alternative routing is last, where an agent scanning for the wrong-tool check will find it.

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

Completeness4/5

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

An output schema exists, so return-value explanation isn't required, and the description covers scope (current month), result content, and the two escape hatches to sibling tools. The only thin spot is that nothing signals the default fresh-vs-cached read behavior or the delta-cursor mode, though the schema carries both.

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

Parameters3/5

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

Schema description coverage is 80%, so the schema already explains freshness, projection, includeFreshness and the delta cursor. The description says nothing about any of the five parameters, contributing no meaning beyond structured fields. Baseline 3 is appropriate.

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

Purpose5/5

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

States a specific verb and resource (list groups/categories) plus the payload it returns: current-month dollar budgets, activity and balances. The scope qualifier 'current-month' and the hidden/deleted/internal flag note separate it cleanly from get_month and search_categories without the agent needing to open any schema.

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

Usage Guidelines5/5

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

Explicitly routes the agent: 'Use get_month for other months or search_categories for names.' Both alternatives are named siblings and each is tied to a concrete condition that selects it, leaving nothing to inference.

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

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