This record as markdown: /tools/109naoki-minimal-mcp-server/echo.md
What echo does on Minimal
AI agents call echo to retrieve information from Minimal without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Why echo is rated Low
This is a simple echo function that retrieves and returns the exact input provided. It performs no operations on data beyond retrieval, creates no new data, executes no commands, and has no side effects. It is purely informational and read-like in nature, making it the lowest-risk category.
From the tool's definition Tool name: 'echo'. Description: '入力されたメッセージをそのまま返す簡単なツール' (translates to 'A simple tool that returns the input message as is'). The tool accepts input and returns it without modification or side effects.
Attacks that exploit this kind of access
The rule that runs echo safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Minimal, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For echo, this is the rule to start with:
echo is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Minimal, apply this rule, and every echo call is checked against it from then on.
Questions about echo
入力されたメッセージをそのまま返す簡単なツール. It is categorised as a Read tool in the Minimal MCP Server, which means it retrieves data without modifying state.
Register the Minimal 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 Minimal. Nothing to install.
echo is a Read tool with low risk. Read-only tools are generally safe to allow by default.
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.
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.
echo is provided by the Minimal MCP server (109naoki/minimal-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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