excel_create_native_chart · Excel Finance MCP: Risk & Policy

WHAT IT DOES

What excel_create_native_chart does on Excel Finance MCP

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

WHY IT NEEDS A POLICY

Why excel_create_native_chart needs a policy

This tool creates or modifies Excel files by generating chart visualizations. File creation is a reversible Write operation. Severity is medium because unintended chart creation could clutter files or overwrite existing charts, but the impact is localized to the workbook and easily undone. Confidence is high given the explicit 'create' verb and clear file-creation intent in the description.

From the tool's definition Tool name 'excel_create_native_chart' and description 'Create a native Excel chart file' indicate file creation and modification of Excel workbooks. The server context emphasizes 'creating Excel workbooks' as a core capability.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

excel_create_native_chart Rate-limited

excel_create_native_chart 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": {
    "excel_create_native_chart": {
      "limits": [
        {
          "counter": "excel_create_native_chart_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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 Finance MCP, so you can run agents against it safely.

FAQ

Questions about excel_create_native_chart

What does the excel_create_native_chart tool do? +

Create a native Excel chart file with data visualization. It is categorised as a Write tool in the Excel Finance MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on excel_create_native_chart? +

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

What risk level is excel_create_native_chart? +

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

Can I rate-limit excel_create_native_chart? +

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

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

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