Step 3.5 Flash 2603 is optimized for high-frequency agentic and coding workflows with improved token efficiency and faster reasoning. NOTE: This model runs via StepFun, which may log and train on your prompts.
Added Apr 14, 2026
Context Window
256K
Max Output
256K
Avg output tokens (7d)
3.7K tokens
Input Price (Auto)
$0.10/1M
Output Price (Auto)
$0.30/1M
Capabilities
Benchmarks
Benchmarks
Performance metrics and benchmarks
Sourced from Artificial Analysis.
Intelligence Index
17.0
Agentic work
T²-Bench Telecom (legacy)
Legacy fallback · Conversational AI agents in dual-control scenarios
87.4%
Better than 81% of models compared
Document reasoning
AA-LCR v1.1
Long context reasoning with updated grading
63.0%
Better than 54% of models compared
Reasoning
HLE
Humanity's Last Exam
24.5%
Better than 74% of models compared
IFBench
Instruction-following benchmark
66.5%
Better than 79% of models compared
CritPt
Research-level physics reasoning
2.3%
Coding
Terminal-Bench Hard (legacy)
Legacy fallback · Agentic coding and terminal use
32.6%
Better than 76% of models compared
Knowledge
AA-Omniscience Accuracy
Proportion of correctly answered questions
24.6%
AA-Omniscience Hallucination Rate
Rate of incorrect answers among non-correct responses
91.3%
Legacy benchmarks
GPQA Diamond (legacy)
Graduate-level scientific reasoning
82.6%
Better than 71% of models compared
AA-LCR (unversioned / legacy)
Long context reasoning evaluation
63.0%
Better than 54% of models compared
Last updated Sep 29, 2026
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