echo

THE RISK

Low Risk

Why echo needs a policy

The echo tool merely reflects input back to the caller with no data retrieval, modification, deletion, code execution, or financial impact. It is a read-only utility operation with minimal security risk.

From the tool's definition Tool name 'echo' and description 'Echo a message back to the user' indicate a simple diagnostic or test function that returns user input without side effects.

Documented attack patterns abuse exactly the kind of access echo gives an agent:

POLICY

How to control echo

PolicyLayer is an MCP gateway — it sits between your AI agents and VaultAssist, and nothing reaches the server without passing your rules. This is the rule we recommend for echo:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "echo": {}
  }
}

echo is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register VaultAssist — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about echo

What does the echo tool do? +

Echo a message back to the user. It is categorised as a Read tool in the VaultAssist MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on echo? +

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

What risk level is echo? +

echo is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit echo? +

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

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

echo is provided by the VaultAssist MCP server (3xcaffeine/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every VaultAssist tool call.

Start from VaultAssist, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →