explainx / blog
Anthropic’s /ultrareview runs a multi-agent code review in a remote sandbox—verified findings, not just nits. Official docs: v2.1.86+, Pro/Max get three free runs through May 5, 2026, then extra usage (~$5–$20). How it differs from /review, when to use it, and how explainx.ai thinks about the merge gate.
Apr 22, 2026
A one-day pricing-page shift put Claude Code next to $100 Max plans, drew a sharp transparency backlash, and was rolled back by evening. Anthropic said it was a 2% new-signup experiment with no change for existing customers; Pro keeps Claude Code again. The same week, competitors highlighted their own clarity—another reminder to treat frontier tools as a budget line, not a fixed utility.
Jul 9, 2026
The Claude Code team published the definitive split: model swaps frozen weights (what Claude knows); effort controls files read, tests run, and verification depth. 373K views on X — here's the decision tree builders actually need.
Jul 8, 2026
Anthropic's @ClaudeDevs shared two Fable 5 cost patterns July 8: advisor mode (Sonnet executes, Fable steers) and orchestrator mode (Fable plans, Sonnet researches). explainx.ai maps the benchmarks, API advisor tool, and when to use each.
In April 2026, Anthropic promoted /ultrareview through developer channels (including the ClaudeDevs account on X). The one-line pitch matches the docs: run a deep, multi-agent code review in the cloud so verified bug candidates land back in the CLI or Desktop while you keep working. This post is a builder-friendly summary of the official behavior, cost, and when the tradeoffs make sense—plus explainx.ai’s take on the merge gate.
Source of truth: Find bugs with ultrareview — Claude Code Docs. Features, pricing, and availability are explicitly subject to change; always re-check that page before budgeting or promising behavior to a team.
Per the ultrareview documentation:
/ultrareview.Invocation:
/ultrareview — reviews the diff between the current branch and the default branch, including uncommitted and staged work; the CLI bundles repo state for the sandbox./ultrareview 1234 — PR mode: the sandbox clones GitHub PR #1234 (requires a github.com remote on the repo). If the repo is too large to bundle locally, the tool prompts you to push a branch and use PR mode instead.While it runs: docs cite ~5–10 minutes typically, as a background task. Use /tasks to list running and completed reviews, open details, or stop a run (stopping archives the cloud session; partial results are not returned). Findings arrive as notifications with file, line, and explanation so you can ask Claude to fix in-thread.
Setup: claude update (per social posts and docs), and /login with a Claude.ai account if you have been on API-key-only auth.
The docs include a direct comparison; we repeat it here because the decision is the whole product story:
/review | /ultrareview | |
|---|---|---|
| Runs | locally in your session | remote cloud sandbox |
| Depth | single-pass review | multi-agent + verification |
| Time | seconds to a few minutes | ~5–10 minutes |
| Cost | normal plan usage | free trials (see below), then extra usage |
| Best for | fast iteration | substantial pre-merge changes |
Plain language: Inner loop → /review. Before you merge something high-risk (auth, migrations, security-sensitive paths) → consider /ultrareview if the scope justifies time and money.
From the same official table (April 2026 text):
/extra-usage.GitHub-integrated Code Review (research preview for Team and Enterprise, PR comments from agent teams) is a related but separate product surface from the CLI /ultrareview command; do not conflate the two when planning org rollout.
The ultrareview page states the feature is not available when using Claude Code through Amazon Bedrock, Google Cloud Vertex AI, or Microsoft Foundry, and not for organizations that have Zero Data Retention enabled. If your compliance posture requires one of those, assume /ultrareview is off the table until vendor docs say otherwise.
explainx.ai teaches agent skills, MCP, and courses—so we care about where automated review fits in a real SDLC:
/ultrareview is strong for broad coverage and verified candidates on a big diff; it does not replace domain experts, threat modeling, or regulatory sign-off when those apply.CLAUDE.md, and skills (see gstack / slash stacks for an extreme open-source example). Use /review liberally; use /ultrareview when the diff deserves cloud depth.Read next: Claude Code, Pro, and the April 2026 pricing story · MCP explainer · Claude for Work hub
Research preview features change. Verify version (claude update), official ultrareview docs, and your plan’s extra usage settings before you rely on this in production release processes.