press_button · Espresso MCP: Risk & Policy

WHAT IT DOES

What press_button does on Espresso

AI agents invoke press_button to trigger actions in Espresso. 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.

WHY IT NEEDS A POLICY

Why press_button needs a policy

This tool triggers an external operation (simulating a hardware/software button press) on a connected Android device. The effect depends on which button is pressed (e.g., HOME, BACK, POWER, VOLUME), and while most presses are reversible, some could trigger destructive or sensitive device actions.

From the tool's definition Simulate a button press on the connected Android device using an Enum button

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

press_button Rate-limited

press_button 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": {
    "press_button": {
      "limits": [
        {
          "counter": "press_button_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Espresso, so you can run agents against it safely.

FAQ

Questions about press_button

What does the press_button tool do? +

Simulate a button press on the connected Android device using an Enum button. It is categorised as a Execute tool in the Espresso MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on press_button? +

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

What risk level is press_button? +

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

Can I rate-limit press_button? +

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

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

press_button is provided by the Espresso MCP server (vs4vijay/espresso-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.