s4_echo_pattern

THE RISK

Low Risk

Why s4_echo_pattern needs a policy

This tool performs no data retrieval, modification, execution, or destructive action. It is a simple echo/reflection utility that accepts a date-formatted string and returns it. This is a read-like operation with zero side effects and minimal blast radius if misused.

From the tool's definition Tool name 's4_echo_pattern' and description 'Echo a date code back. Call with code in YYYY-MM-DD form.' indicate a simple echoing/reflection operation that takes a date string and returns it without modification or side effects.

Documented attack patterns abuse exactly the kind of access s4_echo_pattern gives an agent:

POLICY

How to control s4_echo_pattern

PolicyLayer is an MCP gateway — it sits between your AI agents and Crow, and nothing reaches the server without passing your rules. This is the rule we recommend for s4_echo_pattern:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "s4_echo_pattern": {}
  }
}

s4_echo_pattern 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 Crow — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

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EXPLORE

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FAQ

Questions about s4_echo_pattern

What does the s4_echo_pattern tool do? +

Echo a date code back. Call with code in YYYY-MM-DD form. It is categorised as a Read tool in the Crow MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on s4_echo_pattern? +

Register the Crow MCP server in PolicyLayer and add a rule for s4_echo_pattern: 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 Crow. Nothing to install.

What risk level is s4_echo_pattern? +

s4_echo_pattern is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit s4_echo_pattern? +

Yes. Add a rate_limit block to the s4_echo_pattern 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 s4_echo_pattern completely? +

Set action: deny in the PolicyLayer policy for s4_echo_pattern. 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 s4_echo_pattern? +

s4_echo_pattern is provided by the Crow MCP server (kh0pper/crow). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Crow tool call.

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

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