// MCP TOOL REFERENCE

scrub_secrets

ServerContext Engine MCP Server
CategoryExecute

WHAT IT DOES

What scrub_secrets does on Context Engine MCP Server

AI agents invoke scrub_secrets to trigger actions in Context Engine MCP Server. 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.

THE RISK

High Risk

Why scrub_secrets needs a policy

This tool actively processes and transforms content by detecting and masking sensitive values — it is not a passive read but an operation that modifies the representation of data. It falls under Execute because it triggers a text-transformation operation on arbitrary input.

From the tool's definition 'Scrub secrets from content before sending to LLM' and 'Detects and masks 15+ types of secrets'

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

POLICY

How to control scrub_secrets

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

policy.json

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

scrub_secrets 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.

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

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Context Engine MCP Server tools

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All 50 Context Engine MCP Server tools →

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Go deeper

High-risk tools in Context Engine MCP Server → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about scrub_secrets

What does the scrub_secrets tool do? +

Scrub secrets from content before sending to LLM. Detects and masks 15+ types of secrets: - AWS keys, OpenAI/Anthropic API keys - GitHub tokens, Stripe keys, Firebase/Supabase keys - Private keys (PEM), JWTs, connection strings - Generic API keys and passwords Use this before including user content in prompts. It is categorised as a Execute tool in the Context Engine MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on scrub_secrets? +

Register the Context Engine MCP Server MCP server in PolicyLayer and add a rule for scrub_secrets: 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 Context Engine MCP Server. Nothing to install.

What risk level is scrub_secrets? +

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

Can I rate-limit scrub_secrets? +

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

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

scrub_secrets is provided by the Context Engine MCP Server MCP server (kirachon/context-engine). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Context Engine MCP Server tool call.

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

CHECK YOUR STACK →

Free to start. No card required.

50 Context Engine MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.