container_file_write

Create a file with the provided contents in the working directory, overwriting it if it exists.

SERVERCloudflare SOURCEhttps://builds.mcp.cloudflare.com/sse

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade D, identity verified Pull the record →

This record as markdown: /tools/cloudflare/container-file-write.md

WHAT IT DOES

What container_file_write does on Cloudflare

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

RISK

Why container_file_write is rated Medium

This tool creates or modifies files, which is a Write operation. It is reversible (files can be edited or deleted afterward), so it does not meet the Destructive threshold. Severity is high because uncontrolled file writing in a container could corrupt application state, configurations, or inject malicious content, but the impact is scoped to the container filesystem and reversible.

From the tool's definition Tool description explicitly states: 'Create a file with the provided contents in the working directory, overwriting it if it exists.' The tool modifies data (file creation/overwriting) in a reversible manner.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs container_file_write safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Cloudflare, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For container_file_write, this is the rule to start with:

container_file_write Rate-limited

container_file_write 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": {
    "container_file_write": {
      "limits": [
        {
          "counter": "container_file_write_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Cloudflare, apply this rule, and every container_file_write call is checked against it from then on.

FAQ

Questions about container_file_write

What does the container_file_write tool do? +

Create a file with the provided contents in the working directory, overwriting it if it exists. It is categorised as a Write tool in the Cloudflare MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on container_file_write? +

Register the Cloudflare MCP server in PolicyLayer and add a rule for container_file_write: 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 Cloudflare. Nothing to install.

What risk level is container_file_write? +

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

Can I rate-limit container_file_write? +

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

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

container_file_write is provided by the Cloudflare MCP server (https://builds.mcp.cloudflare.com/sse). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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