snow_field_mapper · Serac MCP: Risk & Policy

WHAT IT DOES

What snow_field_mapper does on Serac

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

WHY IT NEEDS A POLICY

Why snow_field_mapper needs a policy

This tool transforms and writes data into ServiceNow record fields. While the operation is reversible (records can be updated or deleted later), it creates or modifies data objects in the system. The 'high' severity reflects the risk that an AI agent could maliciously map source fields to unintended ServiceNow fields, potentially corrupting records or exposing sensitive data through incorrect field mappings.

From the tool's definition Tool projects/transforms a source object into a new shape and maps fields into ServiceNow record fields. The description explicitly mentions shaping data 'inbound integration payload → ServiceNow record fields', indicating creation or modification of records…

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

snow_field_mapper Rate-limited

snow_field_mapper 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": {
    "snow_field_mapper": {
      "limits": [
        {
          "counter": "snow_field_mapper_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 Serac, so you can run agents against it safely.

FAQ

Questions about snow_field_mapper

What does the snow_field_mapper tool do? +

Project a source object into a new shape using a target-field → source-field mapping. Useful for shaping data between systems (e.g. inbound integration payload → ServiceNow record fields). It is categorised as a Write tool in the Serac MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on snow_field_mapper? +

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

What risk level is snow_field_mapper? +

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

Can I rate-limit snow_field_mapper? +

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

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

snow_field_mapper is provided by the Serac MCP server (serac-labs/serac). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.