replace_value · Ast Editor MCP: Risk & Policy

WHAT IT DOES

What replace_value does on Ast Editor

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

WHY IT NEEDS A POLICY

Why replace_value needs a policy

replace_value modifies code by changing values within an AST (Abstract Syntax Tree) context. This is a reversible write operation—values can be changed back—not destructive deletion. The tool operates on code structure keyed by symbol names across 11 languages, making it capable of altering program logic.

From the tool's definition Tool name 'replace_value' combined with context of AST-targeted code editing server that performs 'structural edits' and 'byte-correct edits'.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

replace_value Rate-limited

replace_value 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": {
    "replace_value": {
      "limits": [
        {
          "counter": "replace_value_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 Ast Editor, so you can run agents against it safely.

FAQ

Questions about replace_value

What does the replace_value tool do? +

replace_value. It is categorised as a Write tool in the Ast Editor MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on replace_value? +

Register the Ast Editor MCP server in PolicyLayer and add a rule for replace_value: 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 Ast Editor. Nothing to install.

What risk level is replace_value? +

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

Can I rate-limit replace_value? +

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

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

replace_value is provided by the Ast Editor MCP server (kambleakash0/ast-editor). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.