file_write_chunk

Append the next chunk of bytes (base64) to an upload started with file_write_begin. Send chunks strictly in order, one at a time. Pass

SERVEROpen Mcp Apps SOURCE@2nd1st/open-mcp-apps

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/2nd1st-open-mcp-apps/file-write-chunk.md

WHAT IT DOES

What file_write_chunk does on Open Mcp Apps

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

RISK

Why file_write_chunk is rated Medium

Tool writes data to files in chunks; reversible but can overwrite existing content with repeated calls.

From the tool's definition Append chunk of bytes to upload; creates/modifies files sequentially

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs file_write_chunk safely

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

file_write_chunk Rate-limited

file_write_chunk 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": {
    "file_write_chunk": {
      "limits": [
        {
          "counter": "file_write_chunk_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 Open Mcp Apps, apply this rule, and every file_write_chunk call is checked against it from then on.

FAQ

Questions about file_write_chunk

What does the file_write_chunk tool do? +

Append the next chunk of bytes (base64) to an upload started with file_write_begin. Send chunks strictly in order, one at a time. Pass. It is categorised as a Write tool in the Open Mcp Apps MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on file_write_chunk? +

Register the Open Mcp Apps MCP server in PolicyLayer and add a rule for file_write_chunk: 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 Open Mcp Apps. Nothing to install.

What risk level is file_write_chunk? +

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

Can I rate-limit file_write_chunk? +

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

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

file_write_chunk is provided by the Open Mcp Apps MCP server (@2nd1st/open-mcp-apps). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on Open Mcp Apps, and thousands of servers like it.

This server

All 32 Open Mcp Apps tools →

Across the catalogue

write_file on 0sec → The MCP Attack Database →

Guides

Govern customer-ops agents →Argument validation →Scoped token →