write_file

THE RISK

Medium Risk

Why write_file needs a policy

This tool creates or modifies files in a repository, which is a reversible Write operation. While it could potentially corrupt code or introduce bugs if misused by an agent, the changes are not irreversible (files can be edited again or reverted via version control), so it does not rise to Destructive severity.

From the tool's definition Tool description explicitly states 'Create or update a single file in a GitHub repository'. The verb 'create or update' is characteristic of Write operations. The sibling tool 'delete_file' exists separately, confirming this tool is reversible modification.

Documented attack patterns abuse exactly the kind of access write_file gives an agent:

POLICY

How to control write_file

PolicyLayer is an MCP gateway — it sits between your AI agents and Gitbridge, and nothing reaches the server without passing your rules. This is the rule we recommend for write_file:

policy.json

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

write_file 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.

Create a free account and register Gitbridge — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Gitbridge tools

Destructive delete_file Delete a file from a GitHub repository. This is a destructive operation — the file will be Write add_issue_comment Add a comment to an existing GitHub Issue Write create_issue Create a new GitHub Issue in a repository Write create_repo Create a new GitHub repository on a personal account or within an organization Write flush_queue Commit all queued writes for a repository in a single GitHub commit. Call queue_write firs Write move_file Move or rename a file. Reads from old path, writes to new path, then returns a GitHub link Write push_multiple_files Create or update multiple files in a single commit using the Git Data API Write queue_write Queue a file write for batch commit. Writes are held in server memory and flushed together

All 16 Gitbridge tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about write_file

What does the write_file tool do? +

Create or update a single file in a GitHub repository. It is categorised as a Write tool in the Gitbridge MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on write_file? +

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

What risk level is write_file? +

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

Can I rate-limit write_file? +

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

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

write_file is provided by the Gitbridge MCP server (iotus/gitbridge-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Gitbridge tool call.

Start from Gitbridge, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →