YNAB MCP Server

Get Budget

get_budget

Read-onlyIdempotent

Retrieve a YNAB budget summary with currency and entity counts, or supply server knowledge to fetch only changed budget data as a delta export.

Instructions

Get a budget summary including name, currency format, and account/category/payee counts. Pass lastKnowledgeOfServer to get a delta export instead: every entity (accounts, payees, categories, months, transactions, scheduled transactions, ...) that changed since that server knowledge, plus the new server_knowledge for the next delta request. A delta request with lastKnowledgeOfServer: 0 returns the full budget export, which can be very large — responses over the YNAB_MAX_RESPONSE_BYTES cap (default 8 MB) are rejected; on big budgets prefer incremental deltas or the dedicated list tools.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`budgetId`	No	Budget ID (uses default if not provided)
`lastKnowledgeOfServer`	No	Delta request server knowledge. When provided, returns changed entities and server_knowledge instead of the summary.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

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

A4.9/5.0

Behavior5/5

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

Annotations already mark this as read-only and idempotent, and the description adds substantial behavioral context: the delta response includes changed entities plus new server_knowledge, responses over YNAB_MAX_RESPONSE_BYTES are rejected, and the default cap is 8 MB. This goes well beyond the annotation hints.

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?

Three sentences, front-loaded with the primary purpose, followed by the delta mode and a practical size-limit warning. Every sentence earns its place and the structure is efficient.

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

Completeness5/5

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

Given the output schema exists, return values need no explanation. The description covers both usage modes, the special lastKnowledgeOfServer: 0 behavior, the size cap, and alternatives for large budgets. An agent has everything needed 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 100%, so the baseline is 3. The description adds meaningful parameter behavior beyond the schema by explaining that lastKnowledgeOfServer: 0 returns the full budget export and that large responses may be rejected, plus guidance to prefer incremental deltas. This is extra semantic value, though some delta semantics are already present in the schema.

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?

The description states a specific verb and resource ('Get a budget summary') and enumerates the exact contents (name, currency format, counts). It also describes the delta-export alternative, which clearly distinguishes this tool from siblings like get_budget_settings and list_budgets.

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?

The description explicitly explains when to use the delta mode versus the summary mode, warns that lastKnowledgeOfServer: 0 returns a very large full export, and directs users to prefer incremental deltas or dedicated list tools on big budgets. This is explicit when/when-not guidance with named alternatives.

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