execute_vba · Excel MCP Server MCP: Risk & Policy

WHAT IT DOES

What execute_vba does on Excel MCP Server

AI agents invoke execute_vba to trigger actions in Excel MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why execute_vba needs a policy

VBA execution is a classic code execution vector with critical severity because: (1) VBA can access the entire Windows API and COM object model, enabling file system operations, network access, and system command execution; (2) it operates with the privileges of the Excel/user process; (3) the tool accepts arbitrary code as input with minimal restrictions (only MsgBox stripping); (4) impact depends entirely on the…

From the tool's definition Tool explicitly performs "Execute VBA code" with arbitrary code execution capability. VBA (Visual Basic for Applications) is a full programming language that can interact with the Windows system, file system, network, and external applications.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

execute_vba Rate-limited

execute_vba stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "execute_vba": {
      "limits": [
        {
          "counter": "execute_vba_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about execute_vba

What does the execute_vba tool do? +

Execute VBA code in an open workbook (live Excel only, cannot use with closed files). Code is wrapped in a Sub automatically if needed. MsgBox calls are stripped. Temp modules are cleaned up after execution. It is categorised as a Execute tool in the Excel MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on execute_vba? +

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

What risk level is execute_vba? +

execute_vba is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit execute_vba? +

Yes. Add a rate_limit block to the execute_vba 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 execute_vba completely? +

Set action: deny in the PolicyLayer policy for execute_vba. 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 execute_vba? +

execute_vba is provided by the Excel MCP Server MCP server (kousunh/excel-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.