scf_update_evidence · Scf MCP: Risk & Policy

WHAT IT DOES

What scf_update_evidence does on Scf

AI agents use scf_update_evidence to create or update resources in Scf — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Scf environment.

WHY IT NEEDS A POLICY

Why scf_update_evidence needs a policy

The tool creates or modifies evidence records within a compliance/risk management platform. This is a Write operation because it reversibly changes data state (upsert semantics allow both insert and update).

From the tool's definition Tool name includes "update" and description states "Upsert an evidence item" — upsert is a reversible create/modify operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

scf_update_evidence Rate-limited

scf_update_evidence 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.

View as policy code

policy.json

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

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about scf_update_evidence

What does the scf_update_evidence tool do? +

Upsert an evidence item. It is categorised as a Write tool in the Scf MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on scf_update_evidence? +

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

What risk level is scf_update_evidence? +

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

Can I rate-limit scf_update_evidence? +

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

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

scf_update_evidence is provided by the Scf MCP server (mcp-server-scf). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.