app_open

Open a .0n application bundle file. Decrypts and extracts the application for local use. Example: app_open({ bundle:

SERVER0nmcp SOURCE0nmcp

High RISK CLASS

Category Execute

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-0nork-0nmcp/app-open.md

WHAT IT DOES

What app_open does on 0nmcp

AI agents invoke app_open to trigger actions in 0nmcp. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.

RISK

Why app_open is rated High

Opening and decrypting an application bundle triggers an extraction and decryption process — this is an active operation with side effects (files written to disk, decryption performed) rather than a simple read. It qualifies as Execute because it runs a multi-step operation (decrypt + extract) whose effects depend on the bundle argument.

From the tool's definition 'Open a .0n application bundle file. Decrypts and extracts the application for local use.'

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs app_open safely

PolicyLayer is an MCP gateway: it sits between your AI agents and 0nmcp, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For app_open, this is the rule to start with:

app_open Rate-limited

app_open stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "app_open": {
      "limits": [
        {
          "counter": "app_open_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect 0nmcp, apply this rule, and every app_open call is checked against it from then on.

FAQ

Questions about app_open

What does the app_open tool do? +

Open a .0n application bundle file. Decrypts and extracts the application for local use. Example: app_open({ bundle:. It is categorised as a Execute tool in the 0nmcp MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on app_open? +

Register the 0n MCP server in PolicyLayer and add a rule for app_open: 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 0nmcp. Nothing to install.

What risk level is app_open? +

app_open is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit app_open? +

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

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

app_open is provided by the 0n MCP server (0nmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on 0n, and thousands of servers like it.

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Guides

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