[::] Agentic Stacks

Claude Fable 5 vs Grok 4.3

Pick two tools from the same category to compare side-by-side.

Claude Fable 5
Anthropic's most capable widely released model, built for demanding reasoning and long-horizon agentic work.
Grok 4.3
xAI's flagship API model, billed as its most intelligent and fastest, with strong agentic tool calling.
Category modelmodel
Vendor type commercialcommercial
Pricing usageusage
Strengths
  • + Vendor-stated state-of-the-art on nearly all tested benchmarks, with the lead growing on longer, more complex tasks
  • + 1M-token context window and up to 128k output tokens per request
  • + Built for long-horizon autonomous agent work with memory tool, compaction, and programmatic tool calling
  • + Server-side fallback parameter and fallback credit simplify refusal handling
  • + Aggressive pricing ($1.25 input / $2.50 output per million tokens) for a 1M-context flagship
  • + Vendor-reported leadership in agentic tool calling and instruction following
  • + Companion multi-agent variant (grok-4.20-multi-agent) targeted at agentic workloads
Tradeoffs
  • − Premium pricing: $10 per million input tokens and $50 per million output tokens
  • − Safety classifiers can refuse requests (vendor says under 5% of sessions on average, sometimes catching harmless ones), so integrations must handle stop_reason refusal
  • − 30-day data retention required; not available under zero data retention
  • − Stated knowledge cutoff of November 2024 is older than competing flagships
  • − Rapid model churn; xAI retired eight legacy models (including grok-3) in May 2026, so pinned integrations need active migration
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