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leanstral-1-5

Tool Calling Structured Output

Leanstral 1.5 is an updated Lean 4 formal proof engineering model from Mistral AI, optimized for automated theorem proving and autoformalization. It has 119B total parameters with 6.5B active and supports a 256K token context window. It supports native function calling and structured output.

Providers 1
Released May 27, 2026
Input Modalities text
Output Modalities text
Tarsk Use coding

Available Providers (1)

Provider Model ID Input Cost Output Cost Context Max Output Docs
Requesty leanstral-1-5 $0/MTok $0/MTok 262.1K 32.8K

Capabilities

Reasoning
Tool Calling
Attachments
Open Weights
Structured Output