Compute the 4-byte function selector for a Solidity function signature
AI agents call get_function_selector 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.
Function selector computation is a standard cryptographic hashing operation (keccak256 of signature, take first 4 bytes) used in smart contract interaction. It reads input and returns a derived value without creating, modifying, deleting, or executing anything. No network calls, state changes, or financial impact. This is informational/computational only, placing it clearly in the Read category with low severity.
From the tool's definition Tool computes a 4-byte function selector from a Solidity function signature. This is a pure deterministic computation with no side effects, data modification, or external state interaction. It retrieves/derives computed information only.
Documented attack patterns abuse exactly the kind of access get_function_selector 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 get_function_selector:
{
"version": "1",
"default": "deny",
"tools": {
"get_function_selector": {}
}
}get_function_selector is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Compute the 4-byte function selector for a Solidity function signature. 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 get_function_selector: 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.
get_function_selector 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 get_function_selector 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 get_function_selector. 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.
get_function_selector 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.
Free to start. No card required.
1240 BNB Chain MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.