echo_env_var

Echoes the MY_ENV_VAR environment variable

SERVERMcp Test Servers SOURCEmsfeldstein/mcp-test-servers

Low RISK CLASS

Category Read

Parameters 00 required

Recommended Allowedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/mcp-test-servers/echo-env-var.md

WHAT IT DOES

What echo_env_var does on Mcp Test Servers

AI agents call echo_env_var to retrieve information from Mcp Test Servers without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

RISK

Why echo_env_var is rated Low

This tool retrieves and displays environment variable data. It performs a read operation with no capability to modify, delete, or execute external commands. Severity is low because the blast radius of misuse is limited to exposure of a single environment variable value.

From the tool's definition Tool echoes an environment variable (MY_ENV_VAR). The verb 'echoes' indicates retrieval/output of an existing value with no modification or side effects.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs echo_env_var safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Mcp Test Servers, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For echo_env_var, this is the rule to start with:

echo_env_var Allowed

echo_env_var is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

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

ALLOW ONLY THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Mcp Test Servers, apply this rule, and every echo_env_var call is checked against it from then on.

FAQ

Questions about echo_env_var

What does the echo_env_var tool do? +

Echoes the MY_ENV_VAR environment variable. It is categorised as a Read tool in the Mcp Test Servers MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on echo_env_var? +

Register the Mcp Test Servers MCP server in PolicyLayer and add a rule for echo_env_var: 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 Mcp Test Servers. Nothing to install.

What risk level is echo_env_var? +

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

Can I rate-limit echo_env_var? +

Yes. Add a rate_limit block to the echo_env_var 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_env_var completely? +

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

echo_env_var is provided by the Mcp Test Servers MCP server (msfeldstein/mcp-test-servers). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on Mcp Test Servers, and thousands of servers like it.

This server

All 67 Mcp Test Servers tools →

Across the catalogue

The MCP Attack Database →

Guides

Roll out MCP under one policy →Data exfiltration →MCP token cost →