Convert smallest unit value to human-readable format (e.g., wei to ETH)
AI agents call format_units to retrieve information from BNB Chain MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This is a stateless formatting utility that takes a numeric input and returns a formatted string representation. It retrieves no data from external systems, modifies nothing, executes no code or commands, and cannot cause irreversible changes.
From the tool's definition Tool description states it 'Convert[s] smallest unit value to human-readable format (e.g., wei to ETH)' — a pure data transformation operation with no side effects, no external state modification, and no code execution.
Documented attack patterns abuse exactly the kind of access format_units gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and BNB Chain MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for format_units:
{
"version": "1",
"default": "deny",
"tools": {
"format_units": {}
}
}format_units is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Convert smallest unit value to human-readable format (e.g., wei to ETH). It is categorised as a Read tool in the BNB Chain MCP MCP Server, which means it retrieves data without modifying state.
Register the BNB Chain MCP server in PolicyLayer and add a rule for format_units: 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 BNB Chain MCP. Nothing to install.
format_units 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 format_units 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 format_units. 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.
format_units is provided by the BNB Chain MCP server (nirholas/bnbchain-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 1240 BNB Chain MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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1240 BNB Chain MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.