add_note

THE RISK

Medium Risk

Why add_note needs a policy

The tool creates or registers a new note resource, which is a reversible write operation. It does not execute arbitrary code, delete data irreversibly, or involve financial transactions. The notification side effect (list_changed) is a normal consequence of the write action.

From the tool's definition Tool description states it 'Registers a new demo://note/N resource', which is a create operation that adds a new note resource to the system.

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

POLICY

How to control add_note

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

policy.json

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

add_note 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.

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

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More MCP from Scratch Server tools

Execute route_support_ticket Classifies a support message via sampling/createMessage, then routes it using server-side Execute unstable Throws on purpose to demonstrate handler exceptions → isError. Write publish_status Updates demo://status and notifies subscribers. Write register_extra_tool Adds the greet tool at runtime and notifies tools/list_changed. Read divide Divides a by b. Returns a tool error when b is zero. Read echo Returns its input Read get_time Returns the server clock as an ISO-8601 timestamp. Read greet Returns a short greeting (registered dynamically).

All 12 MCP from Scratch Server tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about add_note

What does the add_note tool do? +

Registers a new demo://note/N resource and notifies list_changed. It is categorised as a Write tool in the MCP from Scratch Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_note? +

Register the MCP from Scratch Server MCP server in PolicyLayer and add a rule for add_note: 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 from Scratch Server. Nothing to install.

What risk level is add_note? +

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

Can I rate-limit add_note? +

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

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

add_note is provided by the MCP from Scratch Server MCP server (pguso/mcp-from-scratch). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every MCP from Scratch Server tool call.

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

CHECK YOUR STACK →