tx_cancel

Cancel a pending BTC transaction via RBF (sends funds back to self).

SERVERBitcoin wallet MCP server SOURCEmarkmhendrickson/mcp-server-bitcoin

Critical RISK CLASS

Category Financial

Parameters 00 required

Recommended Approval-gatedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/markmhendrickson-mcp-server-bitcoin/tx-cancel.md

WHAT IT DOES

What tx_cancel does on Bitcoin wallet MCP server

AI agents use tx_cancel to commit financial operations through Bitcoin wallet MCP server, usually the final step of a payment, billing, or trading workflow. A call moves real money.

RISK

Why tx_cancel is rated Critical

This tool broadcasts a replacement Bitcoin transaction using Replace-By-Fee (RBF) to cancel a pending transaction. It moves funds on the Bitcoin network — even though the destination is 'self', it still commits a financial operation by broadcasting a new transaction with higher fees, consuming those fees irreversibly.

From the tool's definition Cancel a pending BTC transaction via RBF (sends funds back to self)

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs tx_cancel safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Bitcoin wallet MCP server, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For tx_cancel, this is the rule to start with:

tx_cancel Approval-gated

Any call to tx_cancel is blocked until a human approves it. The rest of the server keeps working.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "tx_cancel": {
      "deny_if": [
        {
          "conditions": [],
          "on_deny": "Requires human approval."
        }
      ]
    }
  }
}

GATE THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Bitcoin wallet MCP server, apply this rule, and every tx_cancel call is checked against it from then on.

FAQ

Questions about tx_cancel

What does the tx_cancel tool do? +

Cancel a pending BTC transaction via RBF (sends funds back to self). It is categorised as a Financial tool in the Bitcoin wallet MCP server MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on tx_cancel? +

Register the Bitcoin wallet MCP server MCP server in PolicyLayer and add a rule for tx_cancel: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Bitcoin wallet MCP server. Nothing to install.

What risk level is tx_cancel? +

tx_cancel is a Financial tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit tx_cancel? +

Yes. Add a rate_limit block to the tx_cancel rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block tx_cancel completely? +

Set action: deny in the PolicyLayer policy for tx_cancel. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides tx_cancel? +

tx_cancel is provided by the Bitcoin wallet MCP server MCP server (markmhendrickson/mcp-server-bitcoin). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on Bitcoin wallet MCP server, and thousands of servers like it.

This server

All 93 Bitcoin wallet MCP server tools → Critical-risk tools on this server →

Across the catalogue

All critical-risk MCP tools → The MCP Attack Database →

Guides

Govern MCP payment tools →Human-in-the-loop →Tool call approval →