AI agents use approve_token to create or update resources in Waiaas — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Waiaas environment.
Token approval (ERC-20 approve) is a write operation that modifies the blockchain state by increasing allowances, enabling subsequent transfers or DeFi operations by another party. While reversible (approval can be set to 0), misuse could lead to unauthorized fund access if an AI agent approves excessive amounts to a malicious contract.
From the tool's definition Tool name 'approve_token' on a crypto wallet MCP server; combined with sibling tools like 'aave_borrow', 'aave_supply', 'add_liquidity', 'bridge', and 'call_contract', this server performs financial operations.
Documented attack patterns abuse exactly the kind of access approve_token gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Waiaas, and nothing reaches the server without passing your rules. This is the rule we recommend for approve_token:
{
"version": "1",
"default": "deny",
"tools": {
"approve_token": {
"limits": [
{
"counter": "approve_token_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}approve_token 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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approve_token. It is categorised as a Write tool in the Waiaas MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Waiaas MCP server in PolicyLayer and add a rule for approve_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 Waiaas. Nothing to install.
approve_token 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 approve_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 approve_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.
approve_token is provided by the Waiaas MCP server (minhoyoo-iotrust/waiaas). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Waiaas, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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126 Waiaas tools catalogued and risk-classified — across an index of 43,000+ MCP servers.