GCF
A wire format for structured data exchanged between LLMs and tools, designed to need far fewer tokens than JSON while staying schema-free, lossless, and readable by a model without special training.
GCF is a data format built for repeated exchanges between a model and its tools across an agentic loop, where the same structured context crosses the model boundary many times. A single payload is described as smaller than the JSON equivalent, and the format also deduplicates repeated structure across turns and sends only deltas when context changes, so a long session with overlapping calls is said to cost much less than resending JSON every turn.
It converts between JSON, YAML, TOML, CSV or MessagePack and decodes back to any of those formats, and is described as schema-free, with lossless round-trips verified across many structured values, in seven language SDKs with no runtime dependencies.