Prepare an ERC20 token transfer transaction for signing. Returns transaction data that can be signed and broadcast.
AI agents use prepareERC20Transfer to create or update resources in MCP Ethers Wallet — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your MCP Ethers Wallet environment.
This tool prepares a transaction for transferring ERC20 tokens, which is a financial asset movement operation. However, it only PREPARES the transaction data without actually executing or broadcasting it — the actual transfer requires a separate signing and broadcast step. Since no funds are moved yet, it falls short of Financial.
From the tool's definition Prepare an ERC20 token transfer transaction for signing. Returns transaction data that can be signed and broadcast.
Documented attack patterns abuse exactly the kind of access prepareERC20Transfer gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Ethers Wallet, and nothing reaches the server without passing your rules. This is the rule we recommend for prepareERC20Transfer:
{
"version": "1",
"default": "deny",
"tools": {
"prepareERC20Transfer": {
"limits": [
{
"counter": "prepareerc20transfer_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}prepareERC20Transfer stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Prepare an ERC20 token transfer transaction for signing. Returns transaction data that can be signed and broadcast. It is categorised as a Write tool in the MCP Ethers Wallet MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the MCP Ethers Wallet MCP server in PolicyLayer and add a rule for prepareERC20Transfer: 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 MCP Ethers Wallet. Nothing to install.
prepareERC20Transfer is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the prepareERC20Transfer 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.
Set action: deny in the PolicyLayer policy for prepareERC20Transfer. 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.
prepareERC20Transfer is provided by the MCP Ethers Wallet MCP server (crazyrabbitltc/mcp-ethers-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP Ethers Wallet, 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.
69 MCP Ethers Wallet tools catalogued and risk-classified — across an index of 43,000+ MCP servers.