cross-chain-message-transfer

THE RISK

High Risk

Why cross-chain-message-transfer needs a policy

Sending a cross-chain message initiates an on-chain transaction that is broadcast to one or more blockchains. This is an external execution with real-world effects (gas fees, state changes, message delivery) that cannot be trivially undone. While not strictly financial (no asset movement), it executes blockchain operations.

From the tool's definition 'Transfers a cross-chain message' — triggers an external cross-chain operation on blockchain infrastructure

Documented attack patterns abuse exactly the kind of access cross-chain-message-transfer gives an agent:

POLICY

How to control cross-chain-message-transfer

PolicyLayer is an MCP gateway — it sits between your AI agents and Hyperlane MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for cross-chain-message-transfer:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "cross-chain-message-transfer": {
      "limits": [
        {
          "counter": "cross-chain-message-transfer_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

cross-chain-message-transfer 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.

Create a free account and register Hyperlane MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Hyperlane MCP Server tools

Financial cross-chain-asset-transfer Transfers tokens/assets between multiple blockchain networks using Hyperlane Execute deploy-chain Deploys a new chain to the Hyperlane network. Execute deploy-warp-route Deploys a warp route. Execute run-relayer Runs a relayer for specified chains. Execute run-validator Runs a validator for a specific chain.

All 6 Hyperlane MCP Server tools →

Execute tools on other servers

Android Forensics ADB MCP Server adb_shell_command EMBA-MCP run_emba_scan Frida Game Hacking MCP remove_breakpoint Procmon request_elevation

Go deeper

High-risk tools in Hyperlane MCP Server → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about cross-chain-message-transfer

What does the cross-chain-message-transfer tool do? +

Transfers a cross-chain message. It is categorised as a Execute tool in the Hyperlane 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 cross-chain-message-transfer? +

Register the Hyperlane MCP Server MCP server in PolicyLayer and add a rule for cross-chain-message-transfer: 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 Hyperlane MCP Server. Nothing to install.

What risk level is cross-chain-message-transfer? +

cross-chain-message-transfer is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit cross-chain-message-transfer? +

Yes. Add a rate_limit block to the cross-chain-message-transfer 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 cross-chain-message-transfer completely? +

Set action: deny in the PolicyLayer policy for cross-chain-message-transfer. 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 cross-chain-message-transfer? +

cross-chain-message-transfer is provided by the Hyperlane MCP Server MCP server (suryansh-23/hyperlane-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Hyperlane MCP Server tool call.

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

CHECK YOUR STACK →