index_mod

THE RISK

Medium Risk

Why index_mod needs a policy

Creating a search index involves writing and persisting indexed data structures to enable future searches. This is a write operation that modifies the local search index state. Severity is medium because while it creates data, the effects are reversible (the index can be deleted/recreated) and limited to the local indexing system, not affecting actual Minecraft installations or mods themselves.

From the tool's definition Tool creates a full-text search index, which is a persistent data structure that indexes decompiled mod source code. The description states 'Create a full-text search index' indicating this tool writes/generates data.

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

POLICY

How to control index_mod

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

policy.json

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

index_mod 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 Minecraft Dev MCP — 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 Minecraft Dev MCP tools

Execute decompile_minecraft_version Decompile an entire Minecraft version. By default downloads the client JAR from Mojang, re Execute decompile_mod_jar Decompile a mod JAR file to readable Java source code. The JAR can be either the original Execute remap_mod_jar Remap a Fabric mod JAR from intermediary mappings to human-readable mappings. Useful for r Write index_minecraft_version Create a full-text search index for decompiled Minecraft source. Enables fast searching wi Read analyze_mixin Analyze and validate Mixin code against Minecraft source. Parses @Mixin annotations, valid Read analyze_mod_jar Analyze a third-party mod JAR file to extract metadata, dependencies, entry points, mixins Read compare_versions Compare two Minecraft versions to find differences in classes or registry data. Useful for Read compare_versions_detailed Compare two Minecraft versions with detailed AST-level analysis. Shows method signature ch

All 20 Minecraft Dev MCP 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 index_mod

What does the index_mod tool do? +

Create a full-text search index for decompiled mod source code. Enables fast searching with search_mod_indexed tool. Use after decompile_mod_jar. It is categorised as a Write tool in the Minecraft Dev MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on index_mod? +

Register the Minecraft Dev MCP server in PolicyLayer and add a rule for index_mod: 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 Minecraft Dev MCP. Nothing to install.

What risk level is index_mod? +

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

Can I rate-limit index_mod? +

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

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

index_mod is provided by the Minecraft Dev MCP server (mcdxai/minecraft-dev-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Minecraft Dev MCP tool call.

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

CHECK YOUR STACK →