next_phase · TDD- MCP: Risk & Policy

WHAT IT DOES

What next_phase does on TDD-MCP

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

WHY IT NEEDS A POLICY

Why next_phase needs a policy

This tool transitions session state from one TDD phase to the next (e.g., Red → Green → Refactor). It modifies the session's current phase/state, which is a reversible write operation. The blast radius is low since it only affects an in-memory or persisted TDD session state, and misuse would at most cause a workflow disruption rather than data loss or financial harm.

From the tool's definition Move to the next phase in the TDD cycle

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

next_phase Rate-limited

next_phase 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": {
    "next_phase": {
      "limits": [
        {
          "counter": "next_phase_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 TDD-MCP, so you can run agents against it safely.

FAQ

Questions about next_phase

What does the next_phase tool do? +

Move to the next phase in the TDD cycle. It is categorised as a Write tool in the TDD-MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on next_phase? +

Register the TDD- MCP server in PolicyLayer and add a rule for next_phase: 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 TDD-MCP. Nothing to install.

What risk level is next_phase? +

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

Can I rate-limit next_phase? +

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

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

next_phase is provided by the TDD- MCP server (tinmancoding/tdd-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.