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calebl

YNAB MCP Server

by calebl

Auto Assign

ynab_auto_assign

Automatically distribute Ready to Assign funds to categories with unmet monthly goals, prioritizing largest shortfalls. Use dryRun to preview assignments before applying.

Instructions

Distributes Ready to Assign across categories whose monthly goal is not yet fully funded, largest shortfall first, until the money runs out. Set dryRun to see the plan without changing anything.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
monthNoThe plan month in ISO format (e.g. 2024-01-01, must be the first of the month), or 'current'. Defaults to 'current'.
dryRunNoReturn the proposed assignments without writing them (default: false)
planIdNoThe plan ID (optional, defaults to YNAB_PLAN_ID; budgetId is a deprecated alias)
budgetIdNoDeprecated alias of planId (still accepted)
maxTotalNoOnly assign up to this many dollars, even if more is available in Ready to Assign

Schema Changelog

Changes observed during successful MCP inspections.

  1. Addedv0.3.0

TDQS

A4.2/5.0
Behavior4/5

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

Annotations already indicate this is a write operation (readOnlyHint=false, idempotentHint=false). The description adds valuable behavioral context: it mutates budget assignments, respects a maxTotal cap, and dryRun prevents changes. It doesn't mention side effects like overwriting existing assignments, but the dryRun disclosure and allocation rule provide solid transparency beyond the annotations.

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?

Two sentences with no filler. The core behavior is front-loaded, and the dryRun safety note is placed second. Every word earns its place.

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 write tool with no output schema, the description explains the core behavior, the dryRun preview option, and the stopping condition. It doesn't describe the return value shape, but the absence of an output schema and the presence of dryRun make the behavior sufficiently clear for an agent to invoke it correctly.

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%, so the schema already documents all five parameters. The description adds context for dryRun ('see the plan without changing anything') and implies maxTotal's role, but doesn't add meaning beyond what the schema provides. Baseline 3 is appropriate.

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 ('Distributes'), a clear resource ('Ready to Assign'), and a precise algorithm (largest shortfall first, until money runs out). It distinguishes itself from siblings like ynab_move_money and ynab_update_category_budget by describing an automated allocation behavior rather than a manual transfer or single-category update.

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?

The description clearly explains what the tool does and when it applies (categories with monthly goals not fully funded), and mentions dryRun for previewing. It doesn't explicitly name alternative tools or state when not to use it, but the algorithm description makes the use case clear enough.

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