AI agents use eth_transfer_token to commit financial operations through PortalMCP — usually the final step of a payment, billing, or trading workflow. A call moves real money.
This tool transfers ERC-20 tokens on the blockchain, which constitutes direct movement of financial assets/money. Even with the executeTransaction=false option available, the primary function is to facilitate financial transfers.
From the tool's definition Tool name 'eth_transfer_token' and description states it 'Transfer ERC-20 tokens' and 'executes the transaction using the configured signer', directly moving cryptocurrency assets on Ethereum blockchain.
Attacks that exploit this kind of access
Transfer ERC-20 tokens. By default executes the transaction using the configured signer. Set executeTransaction=false to only prepare an unsigned transaction for an external wallet. It is categorised as a Financial tool in the PortalMCP MCP Server, which means it involves financial transactions. Block by default and require explicit approval.
Register the Portal MCP server in PolicyLayer and add a rule for eth_transfer_token: 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 PortalMCP. Nothing to install.
eth_transfer_token is a Financial tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the eth_transfer_token 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 eth_transfer_token. 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.
eth_transfer_token is provided by the Portal MCP server (portalfnd/portalmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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