validate_access_widener

Parse and validate Fabric Access Widener files against Minecraft source. Checks that targets exist and suggests fixes. Supports both WSL (/mnt/c/...) and Windows (C:\\...) paths.

ServerMinecraft Dev MCP
CategoryRead

How to control validate_access_widener ↓

WHAT IT DOES

What validate_access_widener does on Minecraft Dev MCP

AI agents call validate_access_widener to retrieve information from Minecraft Dev MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

THE RISK

Low Risk

Why validate_access_widener needs a policy

validate_access_widener is a static analysis tool that reads and validates Access Widener configuration files against Minecraft source code. It performs checks and suggests corrections but does not create, modify, delete, or execute any operations. The 'suggests fixes' refers to recommendations presented to the user, not automatic application of changes.

From the tool's definition Tool performs parsing, validation, and checking operations with no modification capability: 'Parse and validate', 'Checks that targets exist', 'suggests fixes'. The output is informational analysis, not data creation, modification, or deletion.

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

POLICY

How to control validate_access_widener

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 validate_access_widener:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "validate_access_widener": {}
  }
}

validate_access_widener is read-only, so it stays allowed — but 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.

CAP 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 Write index_mod Create a full-text search index for decompiled mod source code. Enables fast searching wit 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

All 20 Minecraft Dev MCP tools →

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about validate_access_widener

What does the validate_access_widener tool do? +

Parse and validate Fabric Access Widener files against Minecraft source. Checks that targets exist and suggests fixes. Supports both WSL (/mnt/c/...) and Windows (C:\\...) paths. It is categorised as a Read tool in the Minecraft Dev MCP MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on validate_access_widener? +

Register the Minecraft Dev MCP server in PolicyLayer and add a rule for validate_access_widener: 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 validate_access_widener? +

validate_access_widener is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit validate_access_widener? +

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

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

validate_access_widener 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 →

Free to start. No card required.

20 Minecraft Dev MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.