edit_file

Make line-based edits to a text file. Each edit replaces exact line sequences with new content. Returns a git-style diff showing the changes made. Only works within allowed directories.

SERVERFilesystem SOURCE@modelcontextprotocol/server-filesystem

Medium RISK CLASS

Category Write

Parameters 32 required

Recommended Rate-limitedsee the rule below

Registry record Grade D, identity verified Pull the record →

This record as markdown: /tools/filesystem/edit-file.md

WHAT IT DOES

What edit_file does on Filesystem

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

Parameter	Type	Required	Description
`path`	string	Yes
`edits`	array	Yes
`dryRun`	boolean	—	Preview changes using git-style diff format

Parameters from the server's own tool schema.

RISK

Why edit_file is rated Medium

The tool creates or modifies file content reversibly through line-based edits, fitting the Write category. Severity is high because uncontrolled file editing could corrupt critical application configs, source code, or system files, though the constraint to 'allowed directories' mitigates blast radius compared to unrestricted filesystem access.

From the tool's definition Tool description states it 'Make[s] line-based edits to a text file' and 'replaces exact line sequences with new content,' indicating data modification capabilities.

Risk signalsAccepts file system path (path)

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs edit_file safely

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

edit_file Rate-limited

edit_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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "edit_file": {
      "limits": [
        {
          "counter": "edit_file_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 Filesystem, apply this rule, and every edit_file call is checked against it from then on.

FAQ

Questions about edit_file

What does the edit_file tool do? +

Make line-based edits to a text file. Each edit replaces exact line sequences with new content. Returns a git-style diff showing the changes made. Only works within allowed directories. It is categorised as a Write tool in the Filesystem MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does edit_file accept? +

edit_file accepts 3 parameters: path, edits, dryRun. Required: path, edits. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on edit_file? +

Register the Filesystem MCP server in PolicyLayer and add a rule for edit_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 Filesystem. Nothing to install.

What risk level is edit_file? +

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

Can I rate-limit edit_file? +

Yes. Add a rate_limit block to the edit_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 edit_file completely? +

Set action: deny in the PolicyLayer policy for edit_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 edit_file? +

edit_file is provided by the Filesystem MCP server (@modelcontextprotocol/server-filesystem). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on Filesystem, and thousands of servers like it.

This server

All 14 Filesystem tools →

Across the catalogue

edit_screen on Stitch MCP Server → The MCP Attack Database →

Guides

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