@zeroindex-ai/mcp-mercury

MCP server exposing read-only Mercury banking APIs to Claude Desktop, Claude Code, Cursor, Zed, and any other Model Context Protocol client.

Lets you ask things like:

• "List my Mercury accounts and current balances."
• "Show me my checking-account transactions from last month."
• "What's the largest expense in my treasury account this quarter?"
• "How much did I spend on Anthropic in May?"

Tools

| Tool | What it does | | ------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | list_accounts | Returns every account in your Mercury workspace (checking, treasury, credit cards) with balances. Run this first — it doubles as the credential check and surfaces account IDs for the other tools. ACH numbers redacted by default (see Privacy). | | get_account | Returns full details for one account by ID. ACH numbers redacted by default (see Privacy). | | list_transactions | Returns transactions for an account, filterable by date range (YYYY-MM-DD) and paginated via limit / offset. |

All three are read-only. No transfers, no recipient management, no destructive actions. Mutating tools deliberately omitted; coming in a later release behind an explicit opt-in.

Privacy

This is a banking server. Two specifics worth stating before you wire it up:

• ACH account and routing numbers are REDACTED by default. Both list_accounts and get_account return accountNumber and routingNumber as "***REDACTED***" unless the caller explicitly passes includeBankNumbers: true. This holds for the very first call the README tells you to make — the raw ACH digits never reach your LLM context just because the model listed or looked up an account. Set the flag to true only when the user has actually asked to see the numbers.
• Transaction details reach the LLM in full — and are NOT redacted. list_transactions returns each transaction's counterpartyName / counterpartyNickname, bankDescription, note, and externalMemo exactly as Mercury stores them. Unlike ACH numbers, these are passed through deliberately: they are the substance of the tool — you cannot answer "how much did I pay Acme in April?" without the counterparty name and amount. That means real third-party names, payee identities, and free-text memos about your business flow into the model's context on every list_transactions call. Treat this as business-sensitive: only point this server at an LLM client whose data handling you trust (see Data flow below), and don't run it against a model or endpoint you wouldn't hand a bank statement to.
• Your Mercury API token authorizes writes, even though this package only calls GET endpoints. Treat it like a banking credential: keep it out of source control, rotate if exposed, and use a dedicated token for this MCP server (not your one general-purpose token).
• Data flow. Mercury → this process → your MCP client → the LLM you've configured. Nothing is cached, persisted, or logged by this server. Pick your LLM client accordingly.

Install

npx -y @zeroindex-ai/mcp-mercury

Configure

You need a Mercury API token. Generate one at app.mercury.com/settings/tokens. See the Privacy section above for handling guidance.

Set as MERCURY_API_TOKEN in your MCP client config (next section).

Use with Claude Desktop

Add to claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/claude_desktop_config.json):

{
  "mcpServers": {
    "mercury": {
      "command": "npx",
      "args": ["-y", "@zeroindex-ai/mcp-mercury"],
      "env": {
        "MERCURY_API_TOKEN": "secret-token-xxxxxxxxxxxxxxxx"
      }
    }
  }
}

Restart Claude Desktop (Cmd+Q and reopen — closing the window doesn't reload the config). Then ask:

Use the mercury list_accounts tool to verify credentials and show my balances.

Use with Claude Code

claude mcp add mercury \
  --env MERCURY_API_TOKEN=secret-token-xxxxxxxxxxxxxxxx \
  -- npx -y @zeroindex-ai/mcp-mercury

Local development

git clone https://github.com/zeroindex-ai/mcp-pack
cd mcp-pack
pnpm install
MERCURY_API_TOKEN=secret-token-xxxx pnpm --filter @zeroindex-ai/mcp-mercury dev

Network

Outbound HTTPS calls are made to api.mercury.com only. No telemetry; nothing else leaves the process. See Privacy above for the data-handling specifics.

License

MIT — see LICENSE at the monorepo root.