AI agents call fetch_balance to retrieve information from Crypto Multi-MCP Hub without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves cryptocurrency balance data with no side effects. It belongs in the Read category as it queries state without creating, modifying, deleting, or executing operations. The presence of similar non-destructive balance tools (erc20_balance, eth_balance) in the sibling set reinforces this classification.
From the tool's definition Tool name 'fetch_balance' indicates retrieval of balance data without modification. The empty description limits certainty, but the name pattern (fetch_*) and context among sibling tools (erc20_balance, eth_balance) strongly suggest a read-only query…
Documented attack patterns abuse exactly the kind of access fetch_balance gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Crypto Multi-MCP Hub, and nothing reaches the server without passing your rules. This is the rule we recommend for fetch_balance:
{
"version": "1",
"default": "deny",
"tools": {
"fetch_balance": {}
}
}fetch_balance is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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fetch_balance. It is categorised as a Read tool in the Crypto Multi-MCP Hub MCP Server, which means it retrieves data without modifying state.
Register the Crypto Multi-MCP Hub MCP server in PolicyLayer and add a rule for fetch_balance: 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 Crypto Multi-MCP Hub. Nothing to install.
fetch_balance is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the fetch_balance 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 fetch_balance. 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.
fetch_balance is provided by the Crypto Multi-MCP Hub MCP server (pellenybe/crypto-mcp-server---by-corax-colab). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Crypto Multi-MCP Hub, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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48 Crypto Multi-MCP Hub tools catalogued and risk-classified — across an index of 43,000+ MCP servers.