YNAB MCP Server

Update scheduled transaction

update_scheduled_transaction

DestructiveIdempotent

Change a scheduled transaction's amount, date, account, payee, category, memo, flag, or repeat frequency in YNAB; provide only fields to update, since omitted fields stay unchanged.

Instructions

Change a scheduled transaction. Fields left out do not change.

Use this when a bill's amount changes, it moves to another day or account, or it repeats on a new schedule. Split scheduled transactions cannot be changed through YNAB's API.

Input Schema

Name	Required	Description
`date`	No	New next date: in the future, at most 5 years out (optional)
`memo`	No	New memo. An empty memo clears it (optional)
`amount`	No	New amount in currency units (optional)
`payee_id`	No	New payee, by ID (optional)
`frequency`	No	New frequency (optional)
`account_id`	No	New account (optional)
`flag_color`	No	New flag color (optional)
`payee_name`	No	New payee by name. Creates it if new (optional)
`category_id`	No	New category (optional)
`transfer_account_id`	No	Make it a transfer with this account (optional)
`scheduled_transaction_id`	Yes	Scheduled transaction to change (required)

Output Schema

Name	Required	Description
`id`	Yes	Unique scheduled transaction identifier
`flag`	No	Flag as 'Name (Color)' format
`memo`	No	User-entered memo
`amount`	Yes	Amount in currency units (negative = spending, positive = income)
`payee_id`	No	Payee ID
`date_next`	Yes	Next occurrence date
`frequency`	Yes	How often it happens
`account_id`	Yes	Account ID
`date_first`	Yes	First occurrence date
`payee_name`	No	Payee name
`category_id`	No	Category ID
`account_name`	No	Account name
`category_name`	No	Category name
`subtransactions`	No	The parts of a split scheduled transaction
`transfer_account_id`	No	For a transfer, the other account

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 26, 2026

TDQS

A4.5/5.0

Behavior4/5

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

The annotations already declare this operation destructive and idempotent. The description adds meaningful behavioral context beyond annotations: omitted fields remain unchanged, and split scheduled transactions cannot be updated. It does not explain the practical consequences of the destructive update, but the annotation covers the safety profile.

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 short sentences, front-loaded with the core action and partial-update rule, followed by usage scenarios and a key API limitation. Every sentence adds useful information without repetition.

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?

For an 11-parameter mutation tool with full schema descriptions, an output schema, and annotations covering safety behavior, the description provides enough context: what the tool changes, how omitted fields behave, when to use it, and a critical unsupported case.

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 description coverage is 100%, so the schema carries most parameter details. The description adds the important partial-update semantic ('Fields left out do not change'), which is not explicit in the schema and affects how all optional parameters should be interpreted.

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 uses a specific verb and resource ('Change a scheduled transaction') and immediately distinguishes the operation from create/delete/enter sibling tools by naming the exact change scenarios: amount, day, account, or recurrence schedule.

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 clear when-to-use guidance ('when a bill's amount changes, it moves to another day or account, or it repeats on a new schedule') and one important exclusion (split scheduled transactions cannot be changed). It stops short of explicitly naming alternative sibling tools to use when this tool does not apply.

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