sparql_update · Mnemosyne MCP: Risk & Policy

WHAT IT DOES

What sparql_update does on Mnemosyne MCP

AI agents invoke sparql_update to trigger actions in Mnemosyne MCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why sparql_update needs a policy

SPARQL UPDATE can perform INSERT, DELETE, DROP, and CLEAR operations on RDF graphs. This spans Write, Destructive, and Execute categories. Since SPARQL UPDATE can irreversibly delete or drop graph data, the most severe applicable category is Destructive. However, the empty description lowers confidence slightly.

From the tool's definition Tool name 'sparql_update' — SPARQL UPDATE is a W3C standard for modifying RDF graph data (INSERT, DELETE, DROP operations). Server description mentions 'SPARQL queries' and 'graph operations'.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

sparql_update Rate-limited

sparql_update stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "sparql_update": {
      "limits": [
        {
          "counter": "sparql_update_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Mnemosyne MCP, so you can run agents against it safely.

FAQ

Questions about sparql_update

What does the sparql_update tool do? +

sparql_update. It is categorised as a Execute tool in the Mnemosyne MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on sparql_update? +

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

What risk level is sparql_update? +

sparql_update is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit sparql_update? +

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

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

sparql_update is provided by the Mnemosyne MCP server (sophia-labs/mnemosyne-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.