Monarch Money MCP Server

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Update Transaction

update_transaction

Idempotent

Update transaction details in Monarch Money—amount, merchant, category, date, notes, goal, visibility, review flag, or owner—leaving any omitted fields untouched.

Instructions

Update a transaction, leaving omitted fields unchanged.

Args: transaction_id: Transaction ID from get_transactions or search_transactions. amount: New amount. merchant_name: New display name, not the read-only plaidName statement text. The API ignores empty names. category_id: New category ID from get_transaction_categories. date: New date in YYYY-MM-DD format. notes: Memo, separate from the merchant name; "" clears it. goal_id: Savings goal ID; "" clears the association. hide_from_reports: Whether to hide the transaction from reports. needs_review: Whether to flag the transaction for review. owner_user_id: Member ID from get_household_members; "" makes it Shared. Omitted/null leaves ownership unchanged. Read verbose transactions to verify ownership; the update response does not include the owner.

Returns updated transaction details. This tool cannot change the transaction ID, account, pending status, attachments, or timestamps. Use update_transaction_splits to change splits and update_recurring_transaction to change a merchant's recurring schedule.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`date`	No
`notes`	No
`amount`	No
`goal_id`	No
`category_id`	No
`needs_review`	No
`merchant_name`	No
`owner_user_id`	No
`transaction_id`	Yes
`hide_from_reports`	No

Output Schema

TableJSON Schema

Name	Required	Description	Default
`transaction`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.5.0Sep 24, 2026

addedInput schema / properties / owner_user_id

Added value: +{
+  "anyOf": [
+    {
+      "type": "string"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "title": "Owner User Id"
+}

First observedv0.3.2May 30, 2026

TDQS

A4.8/5.0

Behavior5/5

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

The description goes far beyond the annotations (idempotentHint, readOnlyHint, etc.) by disclosing specific behaviors: empty strings clear fields, the API ignores empty merchant names, owner_user_id '' makes it Shared, and the update response does not include the owner so one must read verbose transactions to verify ownership. It also lists immutable attributes. This is rich, honest behavioral disclosure.

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 well-structured with a clear opening sentence and bullet-like parameter explanations. Every sentence adds value, and the length is justified given the need to document 10 parameters. It front-loads the core behavior and then systematically covers each field without redundancy.

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?

Given the complexity (10 parameters, 1 required), the description covers all necessary aspects: parameter semantics, special behaviors, exclusions (what cannot be changed), and pointers to relevant sibling tools. It also warns about the response not including owner, which is critical for verifying ownership. No critical information is missing.

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

Parameters5/5

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

Schema coverage is 0%, so the description is the sole source of parameter meaning. It explains every one of the 10 parameters in detail, including formats (date YYYY-MM-DD), sources (transaction_id from get_transactions), special values ('' clears notes/goal_id/owner_user_id), and the distinction between merchant_name and the read-only plaidName. This fully compensates for the lack of schema descriptions.

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 clearly states it updates a transaction and lists the mutable fields. It explicitly names sibling tools (update_transaction_splits, update_recurring_transaction) to distinguish itself, and even states what cannot be changed (ID, account, pending status, etc.). This gives an agent a precise understanding of the tool's scope.

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 provides clear guidance on when to use this tool: it mentions using update_transaction_splits for splits and update_recurring_transaction for recurring schedule changes. However, it does not explicitly mention update_transactions_bulk as an alternative for bulk operations, which is a minor gap given that sibling exists. The 'leaving omitted fields unchanged' instruction is a strong usage guideline.

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