High Risk →

cancel_transaction

Cancel a pending transaction by sending a 0-value transaction to yourself with the same nonce but higher gas

How to control cancel_transaction ↓

What cancel_transaction does on Sperax Ecosystem Crypto & DeFI MCP Server

AI agents invoke cancel_transaction to trigger actions in Sperax Ecosystem Crypto & DeFI MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

High Risk

Why cancel_transaction needs a policy

This tool executes a blockchain transaction (sends a 0-value tx with higher gas to replace a pending one). It triggers an external on-chain operation and permanently alters the transaction state. While the intent is cancellation, it executes a real transaction on-chain with irreversible effects on nonce/gas consumption.

From the tool's definition Cancel a pending transaction by sending a 0-value transaction to yourself with the same nonce but higher gas

Documented attack patterns abuse exactly the kind of access cancel_transaction gives an agent:

How to control cancel_transaction

PolicyLayer is an MCP gateway — it sits between your AI agents and Sperax Ecosystem Crypto & DeFI MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for cancel_transaction:

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "cancel_transaction": {
      "limits": [
        {
          "counter": "cancel_transaction_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

cancel_transaction stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

  1. Create a free account and register Sperax Ecosystem Crypto & DeFI MCP Server — nothing to install.
  2. Add this policy — paste it, or build it visually.
  3. Point your MCP client (Claude, Cursor, anything) at your gateway URL.
RATE-LIMIT THIS TOOL →

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Related tools and policies

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Questions about cancel_transaction

What does the cancel_transaction tool do? +

Cancel a pending transaction by sending a 0-value transaction to yourself with the same nonce but higher gas. It is categorised as a Execute tool in the Sperax Ecosystem Crypto & DeFI MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on cancel_transaction? +

Register the Sperax Ecosystem Crypto & DeFI MCP Server MCP server in PolicyLayer and add a rule for cancel_transaction: 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 Sperax Ecosystem Crypto & DeFI MCP Server. Nothing to install.

What risk level is cancel_transaction? +

cancel_transaction is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit cancel_transaction? +

Yes. Add a rate_limit block to the cancel_transaction 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 cancel_transaction completely? +

Set action: deny in the PolicyLayer policy for cancel_transaction. 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 cancel_transaction? +

cancel_transaction is provided by the Sperax Ecosystem Crypto & DeFI MCP Server MCP server (sperax/sperax-crypto-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Sperax Ecosystem Crypto & DeFI MCP Server tool call.

Start from Sperax Ecosystem Crypto & DeFI MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

Free to start. No card required.

1318 Sperax Ecosystem Crypto & DeFI MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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