replace_signature · Ast Editor MCP: Risk & Policy

WHAT IT DOES

What replace_signature does on Ast Editor

AI agents use replace_signature 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_signature needs a policy

replace_signature modifies code structure (function signatures) without deleting them, placing it in Write rather than Destructive. The empty description reduces confidence slightly, but the server context and naming convention strongly indicate signature replacement.

From the tool's definition Tool name is 'replace_signature'; server is AST-targeted code editing with 'surgical tools for structural edits'. Sibling tools like 'add_method', 'add_parameter', 'delete_in_body' confirm this server performs code modifications.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

replace_signature Rate-limited

replace_signature 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_signature": {
      "limits": [
        {
          "counter": "replace_signature_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_signature

What does the replace_signature tool do? +

replace_signature. 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_signature? +

Register the Ast Editor MCP server in PolicyLayer and add a rule for replace_signature: 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_signature? +

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

Can I rate-limit replace_signature? +

Yes. Add a rate_limit block to the replace_signature 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_signature completely? +

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

replace_signature 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.