set_global_variable · HC3 MCP Server MCP: Risk & Policy

WHAT IT DOES

What set_global_variable does on HC3 MCP Server

AI agents use set_global_variable to create or update resources in HC3 MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your HC3 MCP Server environment.

WHY IT NEEDS A POLICY

Why set_global_variable needs a policy

Setting a global variable is a reversible modification operation. While it can affect system behavior if the variable controls important logic, it does not irreversibly delete data, execute arbitrary code, move funds, or permanently break configurations. The impact depends on what the variable controls, making it Write rather than Execute or Destructive.

From the tool's definition Tool name 'set_global_variable' indicates it modifies data (the value of a global variable). Description states it 'Set the value of a global variable', confirming write semantics. No destructive operation or system-critical side effects implied.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_global_variable Rate-limited

set_global_variable stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_global_variable": {
      "limits": [
        {
          "counter": "set_global_variable_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches HC3 MCP Server, so you can run agents against it safely.

FAQ

Questions about set_global_variable

What does the set_global_variable tool do? +

Set the value of a global variable. It is categorised as a Write tool in the HC3 MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_global_variable? +

Register the HC3 MCP Server MCP server in PolicyLayer and add a rule for set_global_variable: 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 HC3 MCP Server. Nothing to install.

What risk level is set_global_variable? +

set_global_variable is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit set_global_variable? +

Yes. Add a rate_limit block to the set_global_variable 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.

How do I block set_global_variable completely? +

Set action: deny in the PolicyLayer policy for set_global_variable. 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.

What MCP server provides set_global_variable? +

set_global_variable is provided by the HC3 MCP Server MCP server (jangabrielsson/hc3_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.