engine_open
Open a .0n bundle file and extract connections to this machine. Decrypts credentials and saves as individual .0n connection files. Optionally inspect without passphrase to see contents first. Example: engine_open({ bundle:
This record as markdown: /tools/io-github-0nork-0nmcp/engine-open.md
What engine_open does on 0nmcp
AI agents use engine_open to create or update resources in 0nmcp, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your 0nmcp environment.
Why engine_open is rated Medium
This tool decrypts a credential bundle and writes individual connection files to the local machine. It creates new files with sensitive decrypted credentials, making it a Write operation. The severity is high because misuse could expose decrypted credentials and connection secrets to unintended locations or actors.
From the tool's definition Open a .0n bundle file and extract connections to this machine. Decrypts credentials and saves as individual .0n connection files.
Attacks that exploit this kind of access
The rule that runs engine_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 engine_open, this is the rule to start with:
engine_open 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.
The button opens the PolicyLayer dashboard: create your workspace, connect 0nmcp, apply this rule, and every engine_open call is checked against it from then on.
Questions about engine_open
Open a .0n bundle file and extract connections to this machine. Decrypts credentials and saves as individual .0n connection files. Optionally inspect without passphrase to see contents first. Example: engine_open({ bundle:. It is categorised as a Write tool in the 0nmcp MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the 0n MCP server in PolicyLayer and add a rule for engine_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.
engine_open is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the engine_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.
Set action: deny in the PolicyLayer policy for engine_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.
engine_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.
More on 0n, and thousands of servers like it.
This server
Across the catalogue