Claude Sonnet 5.5
Anthropic's latest large language model in the Sonnet series, featuring a million-token context window that supports processing of long codebases and extended conversations. It serves as the default reasoning model for Claude Code.
Core Facts
Artificial Analysis gave Argon an intelligence index score of 53, on par with GPT-6 Astra.
Sonnet 5.5 runs more than 30% faster than Sonnet 5.
Claude Sonnet 5.5 achieved 70.6% on the Terminal benchmark, compared to only 10.3% for the previous generation.
Timeline (last 90 days)
According to the poster's account, Anthropic customer service confirmed that two resolved high-error-rate incidents occurred with Claude Sonnet 5.5 that day, and these errors trigger retries that consume quota faster.
The official status update was posted at 15:09 UTC on October 27, with the status marked as "Identified".
The Claude Sonnet 5.5 model has seen an abnormal rise in request error rates, which the official team has confirmed and is investigating.
The status page did not disclose whether the issue occurred in the model inference layer, the gateway layer, or the quota system.
The issue was marked as resolved at 09:56 UTC, with less than an hour from the start of investigation to confirmed resolution.
Claude Sonnet 5.5 recently experienced a service incident with an elevated request error rate.
The official status page began investigating the elevated request error rate for Claude Sonnet 5.5 at 09:14 UTC.
In Cline v4.1.26, when no model is selected, the Cline provider defaults back to Claude Sonnet 5.5, and that model returns to the top of Cline's recommended list.
At 06:27 UTC, the status was updated to Identified, with the root cause of the Claude Sonnet 5.5 request errors located.
At 06:35 UTC, the status changed to Monitoring, announcing that the fix had been deployed and recovery was being monitored.
40 more timeline events
All Facts (20)
Artificial Analysis gave Argon an intelligence index score of 53, on par with GPT-6 Astra.
80%VerifiedSonnet 5.5 runs more than 30% faster than Sonnet 5.
80%VerifiedClaude Sonnet 5.5 achieved 70.6% on the Terminal benchmark, compared to only 10.3% for the previous generation.
75%VerifiedOpus 5.5 scored 66 on the Terminal agent benchmark, higher than Sonnet's 55 and Astra's 57.9.
70%VerifiedHaiku 5.5 can work as a sub-agent alongside Claude Opus 5.5 and Sonnet 5.5 to complete programming tasks.
65%VerifiedFor performance range figures with extremely wide spans, reaching the upper end of the range often depends on favorable conditions such as specific tasks, specific baseline comparisons, and specific batch sizes.
65%VerifiedEvaluating the per-task cost of large models requires considering both the token unit price and the number of tokens consumed to complete the task; the output token consumption of chain-of-thought reasoning models may increase by several times or even dozens of times.
65%Partially VerifiedThe bundled default model of the cline provider was changed from Claude Sonnet 5.5 to Gemini 4 Argon, because the recommendation list now puts it first.
80%UnverifiedThe default models for multiple providers were switched to Claude Haiku 5.5, including Google Vertex AI (changed from Claude Sonnet 5.5 to Claude Haiku 5.5), Cortecs, DevPass, Eden AI, GitHub Copilot, LLM Gateway, NanoGPT, OpenCode Go, Requesty, and Vivgrid.
70%Partially VerifiedCalculated per thousand repair tasks, Claude Haiku 5.5 costs about $0.70, DeepSeek V4.1 Flash 1017 about $1.35, and MiniMax M3.1 Flash about $4.45 by default and about $0.64 at the low setting.
65%Partially VerifiedThe test covered four vision models: Claude Sonnet 5 (Anthropic), Gemini 3 Flash (Google), Gemini 3.1 Flash-Lite (Google), and GPT-5.4 nano (OpenAI).
65%Partially VerifiedThe overall assessment of GPT-6.1 Sol is that it is a competent model with high token efficiency and competitive pricing, but it is outperformed in dynamic 3D game visual impact by Claude Sonnet 5.5 at the same price point
65%Partially VerifiedSonnet 5.5 is on par with Opus 5.5 in offensive and defensive cybersecurity capabilities, making it the first model in the Sonnet series to adopt equivalent cybersecurity protection mechanisms.
65%Partially VerifiedSonnet 5.5 is the first Sonnet model released with cybersecurity safeguards, where high-risk cybersecurity tasks will explicitly fall back to Sonnet 5
65%UnverifiedOn Terminal Bench, mid-tier Sonnet 5.5 scores 28.8% at approximately $0.83 per task, while Sonnet 5's highest tier only reaches 10.3% at approximately $11.6 per task
60%UnverifiedClaude Sonnet 5.5 is less expensive than Opus 5.5 in terms of pricing.
60%UnverifiedAccording to the poster's account, Anthropic customer service confirmed that two resolved high-error-rate incidents occurred with Claude Sonnet 5.5 that day, and these errors trigger retries that consume quota faster.
50%UnverifiedThe official status update was posted at 15:09 UTC on October 27, with the status marked as "Identified".
50%UnverifiedThe status page did not disclose whether the issue occurred in the model inference layer, the gateway layer, or the quota system.
50%UnverifiedIn Cline v4.1.26, when no model is selected, the Cline provider defaults back to Claude Sonnet 5.5, and that model returns to the top of Cline's recommended list.
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