replace_text · Espresso MCP: Risk & Policy

WHAT IT DOES

What replace_text does on Espresso

AI agents use replace_text to create or update resources in Espresso — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Espresso environment.

WHY IT NEEDS A POLICY

Why replace_text needs a policy

This tool modifies data on an Android device by clearing existing text and entering new text. It is a Write operation (reversible modification of UI state/input fields). It could be misused to alter text fields in apps, but effects are generally reversible and scoped to UI interactions.

From the tool's definition Replace text on the connected Android device by clearing current text and typing new text

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

replace_text Rate-limited

replace_text 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "replace_text": {
      "limits": [
        {
          "counter": "replace_text_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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 replace_text

What does the replace_text tool do? +

Replace text on the connected Android device by clearing current text and typing new text. It is categorised as a Write tool in the Espresso MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on replace_text? +

Register the Espresso MCP server in PolicyLayer and add a rule for replace_text: 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 replace_text? +

replace_text is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit replace_text? +

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

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

replace_text 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.