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How to connect Mercury MCP to Claude

Connect Claude Web, Desktop and Cowork to Mercury MCP. List mercury accounts and current balances, summarize recent mercury card transactions, and more using natural language, with authentication handled for you.

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Mercury MCP is Mercury's official MCP server for read-only business banking data. Use it to safely inspect accounts, balances, transactions, cards, statements, and treasury data.

30 Tools

Introduction

Claude is Anthropic's AI assistant, available on the web, in the desktop app, and on mobile. Cowork is its agent for knowledge work, and it runs on all of those surfaces too. Connected to your apps, Claude can work with your files and services to accomplish complex tasks on your behalf.

This guide walks you through the easiest and most secure way to connect your Mercury account to Claude via Composio Connect, enabling it to list Mercury accounts and current balances, summarize recent Mercury card transactions, find last month’s Mercury bank statements, and more such actions on your behalf without compromising your account security.

Setup is the same on Claude Web, Desktop, and Cowork, and you only need to do it once. The connector is tied to your account, so it's available in all three.

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Codex

Connecting Mercury to Claude Web, Desktop, and Cowork

Two ways to add the Composio connector. Pick whichever you prefer.

1. Add with one click

Click the button. Claude opens with the Composio connector filled in. Click Add, then go to step 2.

Add to Claude

Add manually

In Claude Desktop, click Customize in the left sidebar, then select Connectors and click the + icon at the top.

Claude Desktop connectors screen with Add custom connector selected

Click Add custom connector and paste in the Composio MCP server URL:

bash
https://connect.composio.dev/mcp
Add custom connector dialog with Composio MCP server URL

2. Authorize in your browser

Click Connect. You'll be redirected to a browser window where you can authorize Composio to continue.

Composio authorization screen for Claude Web, Desktop, and Cowork

3. Connect your Mercury account

Back in Claude, ask it to connect to Mercury or give it any Mercury-related task.

For example, ask Claude to:

  • "List Mercury accounts and current balances"
  • "Summarize recent Mercury card transactions"
  • "Find last month’s Mercury bank statements"

It will prompt you to authenticate and authorize access.

That's it. Composio's tools are now available in Claude, and your Mercury account is ready to use.

What is the Mercury Claude Connector, and what's possible with it?

The Mercury MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Mercury account. It provides structured and secure access so your agent can perform Mercury operations on your behalf.

Troubleshooting

1. Why does Claude not use the Composio connector for Mercury?

The connector can show as connected, but Claude must use it in each Mercury conversation.

  • Click + at the lower left of the chat, or type /.
  • Hover Connectors.
  • Turn on Composio.
  • Ask Claude to connect to Mercury again.

2. Why does Claude show an MCP server error before Mercury connects?

Claude can show Couldn't reach the MCP server or Authorization with the MCP server failed when you add the connector for Mercury.

  • Check that the connector URL is https://connect.composio.dev/mcp.
  • Connectors run from Anthropic's cloud, so your device network is usually not the problem.
  • Add the connector again from Customize > Connectors, then ask Claude to connect Mercury.
  • If it fails again, send the error and the ofid_ reference id to support@composio.dev.

3. Why does the Mercury authorization link not work?

The Composio connector is one server. Your Mercury account connects separately when Claude asks for it.

  • If the browser does not open, or the link expires, ask Claude to retry the Mercury connection.
  • Composio creates a fresh Mercury authorization link.
  • Open that link in your browser and finish the Mercury sign-in.

4. Why do Mercury actions fail after they worked before?

The Mercury connection can expire or lose permission.

  • Ask Claude to inspect the Mercury connection.
  • If the connection is unhealthy, disconnect it when Claude prompts you.
  • Reconnect the Mercury account and retry the action.
  • If Claude shows a permission prompt, approve it before Claude changes data in Mercury.
  • If the action still fails with a permission error, check that the connected account has that permission in Mercury itself.

5. How do I switch to a different Mercury account?

Claude can manage the Mercury connection for you.

  • Ask Claude to disconnect or delete the current Mercury account.
  • Ask Claude to connect Mercury again.
  • Open the new Composio authorization link for Mercury.
  • Sign in with the other Mercury account in the browser.
  • After the account connects, ask Claude to retry the Mercury task.

6. Why is my Mercury connection missing in Claude Desktop or on a Team plan?

The connector belongs to your Claude account, so your Mercury connection works in Claude Web, Desktop, and Cowork.

  • In Claude Desktop, open Customize > Connectors.
  • Next to Composio, click ⋮ and click Clear cache.
  • If Mercury tools still do not appear, click ⋮, disconnect, remove the connector, and add it again.
  • On Team or Enterprise, an Owner or Primary Owner must enable the connector before you can connect Mercury.
TOOLS

Supported Tools

Every Mercury MCP action and event your agent gets out of the box.

Getaccount

Get account by ID

Getaccountcards

Retrieve all debit and credit cards associated with a specific account.

Getaccounts

Retrieve a paginated list of accounts.

Getaccountstatements

Retrieve a paginated list of monthly statements for a specific account.

Getattachment

Retrieve attachment details including download URL

Getcurrentdate

Get the current date in the format.

Getcustomer

Retrieve details of a specific customer by their ID

Getinvoice

Retrieve details of an invoice by its ID

Getorganization

Retrieve information about your organization including EIN, legal business name, and DBAs.

Getrecipient

Retrieve details of a specific recipient by ID

Getrecipients

Retrieve a paginated list of all recipients.

Getsaferequest

Retrieve a specific SAFE request by its ID.

Getsaferequests

Retrieve all SAFE (Simple Agreement for Future Equity) requests for your organization.

Gettransaction

Get transaction by ID

Gettransactionbyid

Retrieve a single transaction by its ID.

Gettreasury

Retrieve a paginated list of all treasury accounts associated with the authenticated organization.

Gettreasurystatements

Retrieve a paginated list of statements for a specific treasury account.

Gettreasurytransactions

Retrieve paginated treasury transactions for a specific treasury account.

Getuser

Get user by ID

Getusers

Get all users

Getwebhook

Retrieve details of a specific webhook endpoint by ID

Getwebhooks

Retrieve a paginated list of all webhook endpoints for your organization.

Listcategories

Retrieve a paginated list of all available custom expense categories for the organization.

Listcredit

Retrieve a list of all credit accounts for the organization.

Listcustomers

Retrieve a paginated list of customers.

Listinvoiceattachments

Retrieve a list of all attachments for a specific invoice

Listinvoices

Retrieve a paginated list of invoices.

Listrecipientsattachments

Retrieve a paginated list of all recipient tax form attachments across all recipients in the organization.

Listsendmoneyapprovalrequests

Retrieve a paginated list of send money approval requests for the authenticated organization.

Listtransactions

Retrieve a paginated list of all transactions across all accounts.

FRAMEWORKS

How to build Mercury MCP Agent with another framework

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Codex

Use Mercury MCP with Codex

FAQ

Frequently asked questions

With a standalone Mercury MCP server, the agents and LLMs can only access a fixed set of Mercury tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Mercury and many other apps based on the task at hand, all through a single MCP endpoint.

Yes, you can. Claude Cowork fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Mercury tools.

Yes, absolutely. You can configure which Mercury scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Mercury data and credentials are handled as safely as possible.

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