YNAB MCP Server

Create transactions

create_transactions

Create one or more YNAB transactions in one request, including spending, income, transfers, and splits. Use it to record receipts, payroll, account transfers, or categorized split entries.

Instructions

Create one or more transactions in one request.

Use this to enter spending from a receipt, record income, enter a transfer between accounts, or add a split transaction. Calling this twice enters the transactions twice.

Example entries:

Spending: account_id=, date=2024-03-02, amount=-43.17, payee_name="Kroger", category_id=
Income: amount=2500, payee_name="Acme Payroll", category_id=<Inflow: Ready to Assign>
Transfer: account_id=, amount=-200, transfer_account_id=, no category
Split: amount=-80, payee_name="Target", no category, splits=[ {amount: -50, category_id: }, {amount: -30, category_id: }]

Input Schema

Name	Required	Description	Default
`transactions`	Yes	The transactions to create (required)

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 26, 2026

TDQS

A4.1/5.0

Behavior4/5

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

Annotations already declare this is a non-idempotent, non-destructive write. The description reinforces the non-idempotent behavior with 'Calling this twice enters the transactions twice,' which is exactly the kind of context an agent needs. It does not discuss permissions or partial-failure behavior, but with annotations covering the safety profile this is strong.

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?

The purpose is front-loaded, followed by usage, a duplicate warning, and compact examples. Every sentence carries information an agent needs to construct a correct call.

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?

For a complex batch-mutation tool with nested splits and transfers, the description covers the main entry patterns and the duplication hazard. It omits preconditions like account existence and error/partial-failure behavior, but an output schema exists and the input schema is fully annotated, so only minor gaps remain.

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, but the description adds meaningful example patterns: transfers use transfer_account_id with no category, income uses 'Inflow: Ready to Assign', and splits show component amounts. These examples clarify semantics beyond field-level documentation.

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 first sentence gives a specific verb (Create), resource (transactions), and scope (one or more in one request). It does not explicitly contrast with siblings like update_transactions or import_transactions, but the batch-create intent is unmistakable.

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 lists concrete use cases (receipt spending, income, transfers, splits), which tells an agent when to reach for this tool. It also warns that calling twice duplicates entries, a crucial usage constraint. However, it does not name alternatives or state exclusions.

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