Watchpost for Claude Desktop

Check a purchase before Claude pays.

Watchpost adds a local MCP tool that Claude Desktop can call before a purchase. It runs three checks and returns approve, review, or block. This is a cooperating-agent guardrail: it does not intercept a payment if Claude or another tool skips the Watchpost call.

See supported connectionsHow it works
Connection path
npx @watchpost/mcp install
The CLI opens a browser to confirm your account, writes the connection token into Claude Desktop's claude_desktop_config.json, and asks you to restart the app. Install Node.js with npm first; see /install for prerequisites. Then verify a sample check without paying.
Illustrative verdicts · sample outcomes

What it looks like with Claude Desktop.

Approved14:02
amazon.comUSB-C cable, 6ft, braided
$15.99

Trusted merchant, no listing risks flagged, within all your configured rules. Claude proceeds without asking you.

Review14:02
open-ai-credits.exampleAPI credits, $50, auto-renew
$50.00

Listing has recurring-billing language but Claude marked it one-off. Review it in your dashboard; alerts require setup.

Blocked13:58
too-good-deals.ioPremium subscription, best deal
$199.00

Sample block: the trust score is below your minimum and the listing contains suspicious hidden characters. Claude must follow the decision and stop before payment.

Setup with Claude Desktop

Your setup, step by step.

  1. 01
    Sign up

    Email and a password. No credit card to start. You'll land on a dashboard with sensible defaults already set.

  2. 02
    Set your rules

    Caps per purchase, day, and month. An ask-me threshold for anything above your usual range. Categories you don't buy.

  3. 03
    Run the installer

    On your Mac, Windows, or Linux machine: npx @watchpost/mcp install. The CLI confirms your account in the browser, writes the MCP entry into Claude Desktop's config, and asks you to restart Claude.

  4. 04
    Test the check

    Ask Claude to run Watchpost on a sample purchase before paying. The MCP tool returns approve, review, or block, and its instructions tell Claude to honor the result.

Frequently asked

Specific to Claude Desktop.

Does Claude have to be on a paid Anthropic plan?
Watchpost works wherever your current Claude Desktop plan and build allow local MCP servers. Anthropic can change product availability, so confirm MCP support in Claude Desktop's settings before installing.
What if Claude is using a tool like a browser or Stripe Link to actually pay?
Watchpost runs before the payment step. Claude must submit accurate final purchase details and honor the result before executing the payment tool. The MCP instructions request this behavior; Watchpost cannot stop a payment if those instructions are ignored.
Can I see what Claude tried to buy before I noticed the push?
Yes. The dashboard at watchpost.systems/transactions lists every verdict, with reasoning and outcome. Search by merchant, filter by decision, drill into any one.
What happens to the listing data Claude sends Watchpost?
The purchase details are stored with the verdict so you can review your transaction history and audit what the agent submitted. Listing text may be sent to Anthropic for the manipulation scan. See the privacy policy for the current processor and retention details.

Check the setup for Claude Desktop.

The free plan includes 10 purchase checks a month. Confirm the connection with a sample check before relying on it.

See supported connectionsSee pricing