arcade-ynab-mcp

Overview Schema Source Related Servers Discussions Admin

CreateTransaction

Ynab_CreateTransaction

Create a purchase, income, transfer, or split transaction in a YNAB account by providing account, date, and amount; supports memos, payees, categories, and cleared status.

Instructions

Create a transaction: a purchase, income, a transfer between accounts, or a split.

Input Schema

TableJSON Schema

Name	Required	Description
`date`	Yes	Transaction date (YYYY-MM-DD). Future dates are not allowed.
`memo`	No	Optional memo.
`amount`	Yes	Amount in currency units. Negative for an outflow (spending), positive for inflow.
`cleared`	No	Cleared status.
`plan_id`	No	The YNAB plan (budget) ID. Defaults to 'last-used', the plan the user opened most recently. Use ListPlans to find other plan IDs.
`approved`	No	Mark as approved. Defaults to true, since the user asked for it explicitly.
`payee_id`	No	An existing payee ID.
`account_id`	Yes	The account the transaction belongs to.
`flag_color`	No	Optional flag color.
`payee_name`	No	Payee name. Matches an existing payee by name or creates a new one. Ignored if payee_id is given.
`category_id`	No	Category ID. Leave empty for transfers between budget accounts and splits.
`subtransactions`	No	Split lines. Each has an amount (same sign convention) and usually a category_id. The lines must add up to the transaction amount.
`transfer_account_id`	No	For a transfer, the OTHER account's ID. The amount is from this account's point of view (negative moves money out of account_id). Don't combine with payee_id/payee_name.

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.3.0Oct 4, 2026

TDQS

B3.3/5.0

Behavior3/5

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

Annotations already declare the operation is a non-read-only, non-idempotent, open-world mutation, so the safety profile is covered. The description adds the transaction-type taxonomy (purchase/income/transfer/split) but does not disclose the behavioral consequences of idempotentHint=false (repeated calls create duplicates) or the payee auto-creation side effect, which the schema mentions but the description omits.

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?

A single front-loaded sentence with zero filler that immediately conveys the operation and its variants. Nothing needs trimming or reordering.

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

Completeness3/5

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 need not be explained, and the schema carries the parameter burden. Still, for a 13-parameter mutation involving transfers and splits, the description is thin on when to prefer it over CreateScheduledTransaction or ImportTransactions and on the duplicate-creation risk.

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

Parameters3/5

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

Schema description coverage is 100% and the schema itself richly documents every parameter, including transfer sign conventions and split requirements. The description adds no parameter-level meaning beyond what the schema already provides, so the baseline 3 applies.

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?

States a specific verb and resource ('Create a transaction') and enumerates the four supported shapes (purchase, income, transfer, split), which helps an agent understand the scope. It does not, however, distinguish this from close siblings like Ynab_CreateScheduledTransaction or Ynab_ImportTransactions.

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

Usage Guidelines2/5

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

The description gives no guidance on when to use this tool versus alternatives such as CreateScheduledTransaction (future-dated), ImportTransactions (bulk), or UpdateTransactions. Usage is only implied by the verb 'Create'.

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