Generate HMAC (Hash-based Message Authentication Code)
AI agents call generate_hmac to retrieve information from IT Tools MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
HMAC generation is a pure computational/cryptographic operation with no side effects. It reads input data and a secret key, performs a hash computation, and returns the result. No data is written, deleted, or transmitted. Severity is low as it only computes a local hash value, though misuse could involve leaking secrets if outputs are logged.
From the tool's definition Generate HMAC (Hash-based Message Authentication Code) - this is a cryptographic computation that takes input data and a key and produces a hash value
Documented attack patterns abuse exactly the kind of access generate_hmac gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and IT Tools MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for generate_hmac:
{
"version": "1",
"default": "deny",
"tools": {
"generate_hmac": {}
}
}generate_hmac is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Generate HMAC (Hash-based Message Authentication Code). It is categorised as a Read tool in the IT Tools MCP Server MCP Server, which means it retrieves data without modifying state.
Register the IT Tools MCP Server MCP server in PolicyLayer and add a rule for generate_hmac: 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 IT Tools MCP Server. Nothing to install.
generate_hmac 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 generate_hmac 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 generate_hmac. 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.
generate_hmac is provided by the IT Tools MCP Server MCP server (wrenchpilot/it-tools-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from IT Tools MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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119 IT Tools MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.