MTHDS Language

The declarative, TOML-based file format for defining AI methods without writing code.

Overview

MTHDS (.mthds files) is a domain-specific language for defining AI methods. It lets developers declare concepts, pipes, and pipelines in a structured format that is both human-readable and machine-executable. The philosophy is separation of concerns: method logic is declared in MTHDS, while execution is handled by the Pipelex runtime. This keeps prompts, data flow, and orchestration version-controlled and reviewable.

Domains

Semantic namespaces for organizing related concepts and pipes. Domains provide hierarchical naming and scoping, preventing name collisions across packages. Each .mthds file declares a single domain, and multiple files can contribute to the same domain.

Bundles

A bundle is a complete method package defined in a single .mthds file. It contains a domain declaration, concepts, and pipes, and can optionally designate a main_pipe as the entry point. Bundles are self-contained and can be executed via the CLI or Python API.

Packages & Dependencies

Use METHODS.toml to declare package identity and exports. The current public package-manifest workflow is documented through the lowercase mthds CLI: mthds package init, mthds package list, and mthds package validate.

Cross-Package References

Reference concepts and pipes across package boundaries using the -> operator with fully qualified names. This enables method composition — build complex methods from smaller, reusable packages.

Pure MTHDS Development

Inline concept structures with nested concepts make Pipelex fully usable with just .mthds files and the CLI — no Python code required. Define structured outputs, orchestrate multi-step pipelines, and run everything from the command line.

Language Specification

For the formal language specification, see mthds.ai. For package-manifest details, see Packages.

Packages - METHODS.toml manifests and exports
Concepts - Semantic typing and structured content
Pipe Operators - The operators you can declare in .mthds files