Paranoia Local

A local MCP server that gets a cold, adversarial second opinion on your code changes and plans — from the other frontier coding agent, running on its own subscription, with full read access to your repository.

Install it into Claude Code and reviews are performed by Codex (GPT‑5.6). Install it into Codex and reviews are performed by Claude Code (Fable 5). The MCP server is just the channel between them.

┌──────────────┐   "paranoia: critique this branch"   ┌──────────────┐
│  Claude Code │ ───────────────────────────────────► │ paranoia-local│
│  (your work) │                                       │   (MCP, local)│
└──────────────┘                                       └──────┬───────┘
                                                              │ codex exec (read-only, your repo)
                                                       ┌──────▼───────┐
                                                       │ Codex / GPT-5.6│  ← reads the whole repo,
                                                       │  cold reviewer │    decides what to open
                                                       └──────────────┘

Why

Claude (or Codex) can review its own work, but it reviews with the same biases it wrote with. A different model with a fresh context is a genuine second opinion. This tool packages that into one MCP call.

Compared to an API-key reviewer that only sees a hand-assembled payload, a local agent reviewer is:

• More powerful — it has the entire repository and git history and decides what to read. It opens call-sites, follows the blast radius, checks tests and configs, and reads git history — the things a diff-only reviewer can't.
• Cheaper — it runs on your existing ChatGPT / Claude subscription, not metered API tokens.
• Safer — the reviewer runs read-only (OS sandbox for Codex; a read-only tool allowlist for Claude) inside a throwaway git worktree, so it can't touch your work.

Tools

Tool	What it does
critique_branch	Adversarial review of a git branch/diff or the dirty working tree. Five-section critique (What works / doesn't / Risks / Gaps / Improvements) with [BLOCKER]/[MAJOR]/[MINOR]/[OUT-OF-SCOPE] tags.
critique_plan	Adversarial review of a plan or design doc. With repo_path, the reviewer reads the real code to test the plan's premises about current behaviour — a plan built on an inverted premise is the most dangerous kind.
query	A quick double-check of a single fact or point. Not a full review — lower reasoning effort, a direct answer with citations and a stated confidence level.
rebut	Dispute a specific finding. Resumes the same reviewer session with your counter-evidence; it concedes or holds with fresh citations. Cheaper and higher-resolution than a cold re-round.

Every review returns a session_ref in its footer — pass it to rebut.

Convergence loop

critique_branch and critique_plan take an already_raised array: one-line, file:line-cited claims already accepted from prior rounds. The reviewer is told not to restate them and to hunt for what they missed. Drive the loop from the caller — spawn a fresh review each round feeding the growing already_raised list — until findings converge or drop to noise. (Never paste prior reviewers' prose; just the deduplicated claim + citation.)

Install

Prerequisites

• Python 3.11+
• git on PATH
• The reviewing agent's CLI installed and signed in on a subscription:
  • Codex CLI (codex, ≥ 0.144) signed in with a ChatGPT plan, or
  • Claude Code (claude) signed in with a Claude plan.

Install the server

git clone https://github.com/subvertnormality/paranoia-local
cd paranoia-local
pip install -e .

This puts a paranoia-local executable on your PATH — the command both the Claude Code and Codex MCP entries below launch.

Wire into Claude Code (reviews performed by Codex)

claude mcp add paranoia -- paranoia-local --engine codex

Add to your ~/.claude/CLAUDE.md so it's only used on request:

Never call the paranoia MCP server unless I explicitly ask for adversarial review,
critique, or a second opinion.

Wire into Codex (reviews performed by Claude Code)

Register the server (this writes the [mcp_servers.paranoia] table to ~/.codex/config.toml):

codex mcp add paranoia -- paranoia-local --engine claude

Then you must add the timeout keys — codex mcp add does not set them, and the defaults are far too low. Edit ~/.codex/config.toml so the entry reads:

[mcp_servers.paranoia]
command = "paranoia-local"
args = ["--engine", "claude"]
# REQUIRED: an agentic review is many turns of tool use and runs for minutes.
# Codex's default MCP tool timeout is 60s and startup is 10s, which abort every
# review. Give the tool an hour and startup 30s.
tool_timeout_sec = 3600
startup_timeout_sec = 30

Verify it took:

codex mcp get paranoia
#   tool_timeout_sec: 3600
#   startup_timeout_sec: 30

Timeout gotcha. A full review is many turns of tool use and can run for several minutes. Claude Code's stdio MCP idle timeout (~30 min) is fine out of the box; Codex defaults to a 60-second tool timeout (tool_timeout_sec) and a 10-second startup timeout (startup_timeout_sec), and both must be raised as shown above or every review fails. 3600s is a generous per-call ceiling — a single review is minutes, and a multi-round convergence loop is separate calls, each well under the limit. Raise it further for very large repos at high effort.

Usage

In Claude Code:

"Use paranoia to critique this branch against main. Intent: add overdraft protection to withdraw()."

The agent calls:

{
  "name": "critique_branch",
  "arguments": {
    "repo_path": "/Users/you/Work/my-project",
    "base_ref": "main",
    "head_ref": "HEAD",
    "diff_intent": "Add overdraft protection to withdraw()."
  }
}

Per-repo defaults — .paranoia.toml

Drop a .paranoia.toml at the repo root so callers stop retyping context. Keys at the top level or under [paranoia]. Precedence: call arg > .paranoia.toml > built-in default.

project_summary = "A booking API. Python/FastAPI, Postgres. Auth via short-lived JWTs."
base_ref = "develop"
web_search = true      # allow external methodology/library cross-checks
isolate = true         # review inside a throwaway worktree
# model / effort overrides also honoured

Common arguments

All tools accept:

• engine — override which engine reviews for this one call (codex | claude).
• model — override the reviewer model (defaults to the engine's strongest: gpt-5.6-sol / claude-fable-5).
• effort — low | medium | high. Reviews default to high; query defaults to medium.
• web_search — allow the reviewer to cross-check external methodology/library claims on the web (default true).

Safety model

• Read-only. Codex runs under its OS sandbox (--sandbox read-only); Claude runs with a read-only tool allowlist (Read, Grep, Glob, scoped git reads, web search) and write tools explicitly denied. The reviewer cannot edit your code, run your test suite, or reach the network except for opt-in web search.
• Isolated. Committed reviews run inside a throwaway git worktree of the target ref, so they never collide with your working tree and can review a branch that isn't checked out. (Dirty-working-tree reviews necessarily run in the live repo, read-only.)
• No API keys, no telemetry, no state. The server shells out to a CLI you're already signed into. It writes a local audit record per review to ~/.paranoia/logs/ (provenance + the session ref for rebut) and nothing else.

Rate limits

Reviews draw on your subscription's agentic-usage pool. A heavy convergence loop is many agent turns — on smaller plans you can hit the 5-hour window. Use query (lower effort) for quick checks, and reserve full multi-round critique_branch loops for changes that warrant them.

Development

pip install -e '.[dev]'
python -m pytest        # unit + integration (integration uses fake CLIs; no quota)

Every module is TDD'd. The engine subprocess boundary is dependency-injected, so the whole stack is unit-tested without spending subscription quota; a separate integration test drives the real subprocess runner against fake codex/claude binaries on PATH.

License

MIT © 2026 Andrew Hillel