py-ynab-mcp

by duganth

Overview Schema Source Related Servers Discussions Admin

Python

Remote

update_transaction

Update fields of an existing YNAB transaction by specifying only the fields to change.

Instructions

Update fields of an existing YNAB transaction.

Only provide the fields you want to change.

Args: transaction_id: Transaction UUID to update. account_id: New account UUID. amount: New dollar amount ("-42.50" for outflow). date: New date (YYYY-MM-DD). payee_name: New payee name. payee_id: New payee UUID, including an account transfer payee ID. category_id: New category UUID. Omit when splitting. memo: New memo. cleared: "cleared", "uncleared", or "reconciled". approved: Whether the transaction is approved. subtransactions_json: JSON array of split legs, converting this into a split transaction. Each element: {"amount", "category_id"?, "payee_name"?, "payee_id"?, "memo"?}. Amounts are dollars with the same sign as the parent and must sum to it. Pass amount too, so the legs can be checked against the total. Replaces any existing legs. budget_id: Budget ID. Defaults to last-used budget. dry_run: Validate and preview without updating.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`date`	No
`memo`	No
`amount`	No
`cleared`	No
`dry_run`	No
`approved`	No
`payee_id`	No
`budget_id`	No
`account_id`	No
`payee_name`	No
`category_id`	No
`transaction_id`	Yes
`subtransactions_json`	No

Output Schema

TableJSON Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv0.3.0Sep 8, 2026

addedInput schema / properties / payee_id

Added value: +{
+  "anyOf": [
+    {
+      "type": "string"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "title": "Payee Id"
+}

addedInput schema / properties / subtransactions_json

Added value: +{
+  "anyOf": [
+    {
+      "type": "string"
+    },
+    {
+      "items": {},
+      "type": "array"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "title": "Subtransactions Json"
+}

First observedv0.2.0Jul 12, 2026

TDQS

A4/5.0

Behavior3/5

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

No annotations, so description carries the burden. Mentions dry_run for preview and that subtransactions_json 'Replaces any existing legs', but does not note permanent effects, permissions, or error behavior.

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?

Structured as a compact parameter list with brief, well-organized descriptions. Slightly long due to 13 parameters, but each entry is necessary and no fluff.

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?

Given the complexity of 13 parameters, it covers all parameter meanings and special behaviors like dry_run and replacing subtransactions, though it lacks details about response format or error cases.

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

Parameters5/5

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

All 13 parameters are described, adding semantic meaning beyond the bare schema, including amount sign convention, subtransaction structure, and budget_id default. Schema itself has no descriptions, so this fully compensates.

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?

Clearly states 'Update fields of an existing YNAB transaction' – a specific verb and resource, easily distinguishing it from create, list, and delete transaction tools.

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

Usage Guidelines3/5

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

Provides partial usage guidance with 'Only provide the fields you want to change' and parameter descriptions, but does not explicitly contrast with sibling tools like create_transactions or delete_transaction.

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