High Risk →

shell

Execute shell commands non-interactively via Oculo.

Risk signalsAccepts freeform code/query input (command)

Part of the Oculo server.

shell can trigger actions in Oculo, with no limits today. PolicyLayer puts allow, deny, and rate-limit rules on every call. Live in minutes.

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Free to start. No card required.

AI agents invoke shell to trigger processes or run actions in Oculo. Execute operations can have side effects beyond the immediate call -- triggering builds, sending notifications, or starting workflows. Rate limits and argument validation are essential to prevent runaway execution.

shell can trigger processes with real-world consequences. An uncontrolled agent might start dozens of builds, send mass notifications, or kick off expensive compute jobs. PolicyLayer enforces rate limits and validates arguments to keep execution within safe bounds.

Execute tools trigger processes. Rate-limit and validate arguments to prevent unintended side effects.

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "shell": {
      "limits": [
        {
          "counter": "shell_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

See the full Oculo policy for all 12 tools.

Get this rule live on your own Oculo server in minutes. PolicyLayer enforces it on every call, before it runs.

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View all 12 tools →

These attack patterns abuse exactly the kind of access shell gives an agent. Each links to the full case and the policy that stops it:

Browse the full MCP Attack Database →

Every attack above starts with a tool call. PolicyLayer checks each one against your policy first, so shell only ever does what you allow.

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Other execute tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.

What does the shell tool do? +

Execute shell commands non-interactively via Oculo.. It is categorised as a Execute tool in the Oculo MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on shell? +

Register the Oculo MCP server in PolicyLayer and add a rule for shell: 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 Oculo. Nothing to install.

What risk level is shell? +

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

Can I rate-limit shell? +

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

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

shell is provided by the Oculo MCP server (xidik12/oculo). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Oculo tool call.

Deterministic rules across all 12 Oculo tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.

Free to start. No card required.

4,600+ MCP servers and 31,000+ tools scanned and risk-classified.

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