save_fact

THE RISK

Medium Risk

Why save_fact needs a policy

The tool creates or modifies fact data based on its name. Without a description, confidence is reduced, but the naming convention and context (memory/knowledge management server with save/delete operations) strongly suggest a Write operation rather than Read. It is not Destructive (no irreversible deletion), Financial, or Execute (no code execution implied).

From the tool's definition Tool name 'save_fact' indicates data creation/modification. Description is empty, limiting precision. Sibling tools include 'save_memory' and 'delete_memory', suggesting this server manages persistent state. The 'save_' prefix denotes write operations.

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

POLICY

How to control save_fact

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

policy.json

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

save_fact 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 A-Modular-Kingdom — 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 A-Modular-Kingdom tools

Destructive delete_memory Delete a specific memory by ID. Execute code_execute Execute Python code in a sandboxed subprocess and return stdout/stderr Execute browse_web Control a persistent browser. Actions: navigate (open URL), click (by CSS selector or x,y Execute text_to_speech Convert text to speech using various TTS engines. Can play audio directly or save to file. Write save_memory save_memory Write set_global_rule Set a permanent global rule that persists across all projects and sessions Read analyze_media Analyze image/video files with a local multimodal model via Ollama (e.g., gemma3:4b) Read health_check Check MCP server health and component status

All 14 A-Modular-Kingdom 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 save_fact

What does the save_fact tool do? +

save_fact. It is categorised as a Write tool in the A-Modular-Kingdom MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on save_fact? +

Register the A-Modular-Kingdom MCP server in PolicyLayer and add a rule for save_fact: 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 A-Modular-Kingdom. Nothing to install.

What risk level is save_fact? +

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

Can I rate-limit save_fact? +

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

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

save_fact is provided by the A-Modular-Kingdom MCP server (masihmoafi/a-modular-kingdom). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every A-Modular-Kingdom tool call.

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

CHECK YOUR STACK →