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calebl

YNAB MCP Server

by calebl

List Months

ynab_list_months
Read-only

List every plan month and view its budgeting status summary, making it easy to track budget progress across months.

Instructions

Lists all plan months. Each month contains summary information about budgeting status.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
planIdNoThe plan ID (optional, defaults to YNAB_PLAN_ID; budgetId is a deprecated alias)
budgetIdNoDeprecated alias of planId (still accepted)

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed5 schema fields changedv0.3.0
    • removedInput schema / additionalProperties
      Removed value: -false
    • addedInput schema / properties / budgetId / anyOf
      Added value: +[
      +  {
      +    "description": "Deprecated alias of planId (still accepted)",
      +    "type": "string"
      +  },
      +  {
      +    "type": "null"
      +  }
      +]
    • changedInput schema / properties / budgetId / description
      Previous value: -"The ID of the budget (optional, defaults to YNAB_BUDGET_ID environment variable)"New value: +"Deprecated alias of planId (still accepted)"
    • removedInput schema / properties / budgetId / type
      Removed value: -"string"
    • addedInput schema / properties / planId
      Added value: +{
      +  "anyOf": [
      +    {
      +      "description": "The plan ID (optional, defaults to YNAB_PLAN_ID; budgetId is a deprecated alias)",
      +      "type": "string"
      +    },
      +    {
      +      "type": "null"
      +    }
      +  ],
      +  "description": "The plan ID (optional, defaults to YNAB_PLAN_ID; budgetId is a deprecated alias)"
      +}
  2. Addedv1.0.0

TDQS

A3.8/5.0
Behavior3/5

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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false), and the description adds that each month contains budgeting-status summary information. It does not mention pagination, ordering, or plan scoping details, but for a straightforward read-only list tool the combination of annotations and description is adequate. No contradiction with 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?

The description is two short sentences with no filler, front-loading the action ('Lists all plan months') before clarifying the content of each month. Every sentence 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 simple read-only list tool with optional parameters and no output schema, the description provides the essential context: all plan months are returned, each with summary budgeting information. It could mention ordering or pagination, but the schema covers parameter defaults, so the definition is nearly complete.

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 fully documents planId and budgetId, including the default to YNAB_PLAN_ID and the deprecated alias behavior. The tool description adds no parameter-specific information, but the baseline of 3 applies because the schema carries the load.

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 starts with a specific verb and resource: 'Lists all plan months', making the operation and scope explicit. The second sentence clarifies the return content (budgeting status summaries), which distinguishes this tool from sibling list tools like ynab_list_accounts and ynab_list_plans.

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?

The description implies this tool is for retrieving plan months and their summary budgeting status, but it does not name alternatives or state when not to use it. However, for a simple list operation, the context is reasonably inferred from the description.

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