update_field · Redcap MCP: Risk & Policy

WHAT IT DOES

What update_field does on Redcap

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

WHY IT NEEDS A POLICY

Why update_field needs a policy

The tool updates research data fields in REDCap, which modifies data reversibly. This is a Write operation, not Destructive (reversible via other tools). Severity is high because REDCap manages sensitive research data; field updates could affect study integrity and require audit trails. However, confidence is moderate (0.85) because the description is empty, limiting certainty about scope and side effects.

From the tool's definition Tool name 'update_field' in REDCap (research data management system) context, paired with sibling tools like 'add_field', 'add_instrument', and destructive operations like 'delete_field'. The name and context indicate modification of research data fields.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_field Rate-limited

update_field 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": {
    "update_field": {
      "limits": [
        {
          "counter": "update_field_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 Redcap, so you can run agents against it safely.

FAQ

Questions about update_field

What does the update_field tool do? +

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

How do I enforce a policy on update_field? +

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

What risk level is update_field? +

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

Can I rate-limit update_field? +

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

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

update_field is provided by the Redcap MCP server (msicilia/mcp-server-redcap). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.