AI agents call decode_jwt 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.
This tool only decodes (parses) a JWT token to extract its header and payload components. It performs no writes, executes no code, and has no side effects. The only risk is that a JWT may contain sensitive claims, but the tool itself only reads/parses data locally.
From the tool's definition Decode JWT token (header and payload only)
Documented attack patterns abuse exactly the kind of access decode_jwt 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 decode_jwt:
{
"version": "1",
"default": "deny",
"tools": {
"decode_jwt": {}
}
}decode_jwt is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Decode JWT token (header and payload only). 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 decode_jwt: 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.
decode_jwt 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 decode_jwt 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 decode_jwt. 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.
decode_jwt 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.