schema_redo · Zion MCP: Risk & Policy

WHAT IT DOES

What schema_redo does on Zion

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

PARAMETERS

Parameter	Type	Required
`appExId`	string \| null	—
`projectExId`	string	—
`appVersionExId`	string \| null	—

Parameters from the server's own tool schema.

WHY IT NEEDS A POLICY

Why schema_redo needs a policy

This tool reapplies a previously undone schema change, which modifies the project schema (a reversible write operation). While schema changes can be impactful, this is a redo operation that restores a prior state rather than destroying data irreversibly. It is Write rather than Destructive because the undo/redo mechanism implies reversibility.

From the tool's definition Re-apply the schema change most recently undone via schema_undo

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

schema_redo Rate-limited

schema_redo 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": {
    "schema_redo": {
      "limits": [
        {
          "counter": "schema_redo_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 Zion, so you can run agents against it safely.

FAQ

Questions about schema_redo

What does the schema_redo tool do? +

Re-apply the schema change most recently undone via schema_undo in this session. It is categorised as a Write tool in the Zion MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does schema_redo accept? +

schema_redo accepts 3 parameters: appExId, projectExId, appVersionExId. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on schema_redo? +

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

What risk level is schema_redo? +

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

Can I rate-limit schema_redo? +

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

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

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