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Grok 4.3 vs Claude Opus 4.7 vs GPT-5.5 Coding (May 2026)

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Grok 4.3 vs Claude Opus 4.7 vs GPT-5.5 Coding (May 2026)

Three frontier coding models, three different sweet spots. Claude Opus 4.7 wins repo-scale benchmarks. GPT-5.5 wins terminal agents and token efficiency. Grok 4.3 wins price and 1M-context reach. Here’s the May 2026 breakdown.

Last verified: May 11, 2026

At a glance

PropertyGrok 4.3Claude Opus 4.7GPT-5.5
ReleasedApril 30, 2026 (full API rollout)April 16, 2026 (GA)April 23, 2026
SWE-bench VerifiedNot leading87.6%88.7%
SWE-bench Pro—64.3%57.7% (GPT-5.4)
Terminal-Bench 2.0—69.4%82.7%
MCP-Atlas (tool use)—77.3%—
Context window1M tokens200K1M (degrades less)
Input price (per 1M)$1.25$5(mid-tier)
Output price (per 1M)$2.50$25(mid-tier)
Token efficiency—Baseline~72% fewer output tokens
Native video inputYesNoNo
Real-time dataYes (X)NoNo

Quality: Claude Opus 4.7 still leads SWE-bench

The SWE-bench family of benchmarks is the de facto standard for evaluating real GitHub issue resolution.

  • Claude Opus 4.7 posts 87.6% on SWE-bench Verified — a meaningful jump from Opus 4.6 (80.8%) and the top vendor-reported number through May 11, 2026.
  • Claude Opus 4.7 leads SWE-bench Pro (the harder private set) at 64.3%, beating GPT-5.4 (57.7%) and Gemini 3.1 Pro (54.2%).
  • GPT-5.5 lands at 88.7% on SWE-bench Verified — comparable raw quality, but the harder SWE-bench Pro shows Opus 4.7 still on top.
  • Grok 4.3 isn’t on the SWE-bench top board. Its Artificial Analysis Coding Index of 41.0 puts it ahead of 89% of compared models, but well behind the frontier trio on this specific test.

For repository-scale work — multi-file refactors, debugging that spans modules, long-running agent loops — Claude Opus 4.7 remains the quality leader.

Terminal agents: GPT-5.5 is the clear pick

Terminal-Bench 2.0 measures unattended terminal/shell agent reliability — exactly the workload most DevOps teams care about.

  • GPT-5.5: 82.7% (state-of-the-art)
  • Claude Opus 4.7: 69.4%
  • 13+ point gap

If your agent is running cargo test, npm run build, kubectl apply, terraform plan, or chaining shell tools under a CI runner, GPT-5.5 is the model to pick. The gap is large enough that it’s the dominant factor.

Cost: Grok 4.3 disrupts, GPT-5.5 wins per-task

List prices (per million tokens, May 11, 2026):

ModelInputOutput
Grok 4.3$1.25$2.50
Claude Opus 4.7$5$25
GPT-5.5mid-tiermid-tier
DeepSeek V4-Pro$1.74$3.48
DeepSeek V4-Flash$0.14$0.28

But list price isn’t the right cost metric for agents. The right metric is cost per completed task.

  • GPT-5.5 uses ~72% fewer output tokens than Opus 4.7 for equivalent coding work. Even at similar list prices, GPT-5.5 is materially cheaper per task.
  • Grok 4.3 undercuts on list price by 4-10x vs Opus 4.7 — but you may need more iterations on harder tasks, so the per-task gap narrows.
  • Claude Opus 4.7 is the premium pick — you pay for quality and long-running agent stability.

Context window and harness

Grok 4.3 ships a 1M-token context window at the lowest price of any frontier model. For long-context refactors, large codebase audits, and bulk-doc analysis, this is genuinely disruptive.

GPT-5.5 also reaches 1M tokens and maintains performance past 128K — many models degrade sharply past their nominal window. GPT-5.5 holds.

Claude Opus 4.7 is at 200K tokens — smaller, but the per-token quality is higher.

Equally important: the agent harness matters as much as the model. Cursor’s harness can lift GPT-5.5 noticeably on functionality tests compared to running the model bare. Cline and Aider have their own tuning. The model is only half the story.

Tool use: Claude Opus 4.7 dominates MCP-Atlas

For agents that lean on tools — file operations, web fetches, MCP servers, shell execution — Claude Opus 4.7 leads MCP-Atlas at 77.3%. If your agent is built on Anthropic’s MCP ecosystem, Opus 4.7 is the natural fit.

GPT-5.5 is strong on tool use too but the MCP-specific benchmark is Opus 4.7’s home turf.

Decision tree

Pick Claude Opus 4.7 when:

  • Repo-scale engineering, multi-module refactors, long agent loops
  • MCP-heavy tool workflows (Claude Code, Claude Managed Agents)
  • Quality matters more than per-token cost
  • 200K context is enough for your workload

Pick GPT-5.5 when:

  • Terminal-heavy automation (CI, DevOps, unattended agents)
  • Token cost dominates your bill (high-volume agent pipelines)
  • You need 1M-token context with performance that holds
  • You’re already on the OpenAI / Codex / Cursor stack

Pick Grok 4.3 when:

  • Long-context analysis on a budget (1M tokens at $1.25/$2.50)
  • Real-time X data access matters (news, social, current events)
  • Native video input is part of the workflow
  • You’re cost-sensitive and the task isn’t on the SWE-bench frontier
  • You want a credible third option to keep Anthropic and OpenAI honest

What changed in early May 2026

  • April 16: Claude Opus 4.7 GA (Anthropic, Bedrock, Vertex AI, Foundry, GitHub Copilot)
  • April 23: GPT-5.5 (“Spud”) released
  • April 30: Grok 4.3 full API rollout, ~40% input price cut
  • May 5: ChatGPT Instant tier swapped to GPT-5.5 Instant
  • May 8: GPT-Realtime-2, GPT-Realtime-Translate, GPT-Realtime-Whisper launch
  • May 8: Anthropic introduces “dreaming” for Claude Managed Agents

Three weeks, three frontier upgrades. Coding-agent decisions made before April 16 should be revisited.

What to watch next

  • Claude Mythos preview to public release — Anthropic’s next flagship is in restricted preview with ~50 partners.
  • DeepSeek V4 full launch following the April 24 preview.
  • xAI Grok 5 — rumored for later 2026.
  • Google I/O 2026 (May 19) — Gemini 3.1 Pro updates expected.

Last verified: May 11, 2026 — sources: Anthropic Opus 4.7 release notes, OpenAI GPT-5.5 release notes, xAI Grok 4.3 docs, Oracle Cloud Grok 4.3 docs, Vellum.ai benchmarks, MindStudio benchmarks, OpenRouter, Artificial Analysis, llm-stats.com.