YNAB MCP Server

Get Budget

get_budget

Read-onlyIdempotent

Retrieve a YNAB budget’s name, currency format, and account, category, and payee counts. Pass a delta cursor to fetch changed entities instead of requesting a full export.

Instructions

Get name, currency format, account/category/payee counts. lastKnowledgeOfServer returns changed entities + server_knowledge; zero requests full export, possibly exceeding YNAB_MAX_RESPONSE_BYTES (default 8 MB). Prefer incremental deltas/list tools.

Input Schema

Name	Required	Description	Default
`budgetId`	No
`lastKnowledgeOfServer`	No	Delta cursor; returns changed entities + server_knowledge, not summary.

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 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)"

changedInput schema / properties / lastKnowledgeOfServer / description

Previous value: -"Delta request server knowledge. When provided, returns changed entities and server_knowledge instead of the summary."New value: +"Delta cursor; returns changed entities + server_knowledge, not summary."

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 Get Budget."
```

Changed2 schema fields changedv5.1.1Jul 21, 2026

addedInput schema / properties / lastKnowledgeOfServer

Added value: +{
+  "description": "Delta request server knowledge. When provided, returns changed entities and server_knowledge instead of the summary.",
+  "maximum": 9007199254740991,
+  "minimum": 0,
+  "type": "integer"
+}

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "result": {
+      "description": "Structured result returned by Get Budget."
+    }
+  },
+  "required": [
+    "result"
+  ],
+  "type": "object"
+}

First observedv2.0.0May 28, 2026

TDQS

A4/5.0

Behavior4/5

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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely non-obvious behavior: the implicit-cursor semantics of lastKnowledgeOfServer, that zero means a full export, and the response-size hazard. That is real added context beyond structured fields.

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

Conciseness4/5

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

Two dense sentences with no filler, and the output inventory is front-loaded ahead of the cursor caveat. The phrasing is telegraphic ('zero requests full export'), which costs a little readability but wastes nothing.

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 values needn't be spelled out, and the description correctly focuses on the risky parameter path and the size ceiling. The one gap is the undocumented budgetId (optional, but its omission vs required scope is unstated) — otherwise an agent has enough to call this correctly.

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

Parameters4/5

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

Schema coverage is only 50% (budgetId has no schema description), so the description must compensate. It does so well for lastKnowledgeOfServer — explaining the cursor, the changed-entities-plus-server_knowledge return shape, and the zero/export edge case — which is more than the schema states. budgetId remains unexplained, keeping this short of a 5.

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

Purpose4/5

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

The description gives a concrete inventory of what the call returns (name, currency format, account/category/payee counts), which is specific beyond the bare name 'Get Budget'. It does not, however, distinguish this from the sibling get_budget_settings or list_budgets, so an agent must infer the boundary. Clear purpose, missing sibling differentiation.

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

Usage Guidelines4/5

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

It gives a real routing hint — 'Prefer incremental deltas/list tools' — plus the concrete failure mode (zero cursor may exceed YNAB_MAX_RESPONSE_BYTES, default 8 MB) that should steer an agent away from a full export. It stops short of naming which list tool to use instead or when a full export is actually warranted.

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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