getERC20Allowance

THE RISK

Low Risk

Why getERC20Allowance needs a policy

This tool queries blockchain state to retrieve an ERC20 allowance value. It has no side effects and does not modify, execute, or delete anything. While it operates in a financial domain (ERC20 tokens), the tool itself performs no financial transaction or movement of value — it only reads approval metadata. Thus it is categorized as Read with low severity, as an agent cannot cause direct harm by calling this tool.

From the tool's definition Tool description states 'Get the amount of tokens approved for a spender to use from an owner' — this retrieves existing allowance data without modifying state.

Documented attack patterns abuse exactly the kind of access getERC20Allowance gives an agent:

POLICY

How to control getERC20Allowance

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 getERC20Allowance:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "getERC20Allowance": {}
  }
}

getERC20Allowance is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

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

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More MCP Ethers Wallet tools

Financial prepareERC1155BatchTransfer Prepare an ERC1155 batch transfer transaction for signing. Returns transaction data that c Financial safeBatchTransferERC1155 Safely transfer multiple tokens from the connected wallet to another address in a single t Financial safeTransferERC1155 Safely transfer tokens from the connected wallet to another address Financial safeTransferERC721 Safely transfer an NFT from the connected wallet to another address, with additional data Financial transferERC20 Transfer ERC20 tokens from the connected wallet to another address Financial transferERC721 Transfer an NFT from the connected wallet to another address Financial transferFromERC20 Transfer ERC20 tokens from one address to another (requires approval) Financial transferNFT transferNFT

All 69 MCP Ethers Wallet tools →

Read tools on other servers

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Go deeper

Roll out MCP under one policy → Per-person scoped tokens, one central policy, and full audit across every server your team connects.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →
PolicyLayer vs alternatives → How deterministic, per-call MCP policy compares with gateways, identity layers, and authorisation platforms.

FAQ

Questions about getERC20Allowance

What does the getERC20Allowance tool do? +

Get the amount of tokens approved for a spender to use from an owner. It is categorised as a Read tool in the MCP Ethers Wallet MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on getERC20Allowance? +

Register the MCP Ethers Wallet MCP server in PolicyLayer and add a rule for getERC20Allowance: 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.

What risk level is getERC20Allowance? +

getERC20Allowance is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit getERC20Allowance? +

Yes. Add a rate_limit block to the getERC20Allowance 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 getERC20Allowance completely? +

Set action: deny in the PolicyLayer policy for getERC20Allowance. 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 getERC20Allowance? +

getERC20Allowance 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.

Enforce policy on every MCP Ethers Wallet tool call.

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.

CHECK YOUR STACK →