# tether

> Tether is a small, headless-first harness that lets small local models and frontier models do real work with a tiny prompt: one `act(cmd, stdin)` tool, commands off by default, SQLite for state and memory, a deterministic sandbox and verification gates. Python 3.12+, `pip install tether-sdk`, command `tether`.

## Start here
- [Home](https://igormcsouza.github.io/tether/): what tether is, install, first run.
- [Fix a failing test with a local model](https://igormcsouza.github.io/tether/guides/fix-a-failing-test/): a verification gate decides when the job is done.
- [Use tether from Claude Code, Codex or Cursor](https://igormcsouza.github.io/tether/guides/use-tether-from-your-agent/): MCP setup, the JSON result, exit codes.
- [A pipeline where each stage has its own job](https://igormcsouza.github.io/tether/guides/a-pipeline-with-checks/): stages, per-stage model, tools and gate.
- [Give the model a tool of your own](https://igormcsouza.github.io/tether/guides/add-your-own-tool/): turn a Python function into a command.
- [Run a session on its own branch](https://igormcsouza.github.io/tether/guides/own-branch/): `--worktree`, reading the branch and commit, merging and cleanup.

## Guides
- [Guides index](https://igormcsouza.github.io/tether/tutorial/): every layer, from the first session to multi-agent workflows.
- [CLI and headless sessions](https://igormcsouza.github.io/tether/tutorial/cli-and-headless/): run, watch, resume and read back sessions.
- [Python SDK and custom tools](https://igormcsouza.github.io/tether/tutorial/sdk-and-custom-tools/): Harness, @tool, stdin payloads.
- [Built-in tools](https://igormcsouza.github.io/tether/tutorial/built-in-tools/): done, bash, edit, web, mem, skill, agent.
- [Progressive skills](https://igormcsouza.github.io/tether/tutorial/skills/): package a repeatable job.
- [Async multi-agent orchestration](https://igormcsouza.github.io/tether/tutorial/multi-agent/): spawn, wait, query sub-agents.
- [Gates, memory, pipelines and telemetry](https://igormcsouza.github.io/tether/tutorial/workflows-and-telemetry/): verification gates, pipelines, tether stats.
- [Security and sandbox](https://igormcsouza.github.io/tether/tutorial/security-and-sandbox/): what a session can touch.
- [Use tether inside your harness](https://igormcsouza.github.io/tether/tutorial/agent-interface/): MCP and CLI twins for other agents.
- [Extending tether](https://igormcsouza.github.io/tether/extending/): add tools and model backends.

## Concepts
- [Architecture and literature](https://igormcsouza.github.io/tether/architecture/): why it works this way.
- [Benchmarks](https://igormcsouza.github.io/tether/benchmarks/): Polyglot-Python results and how to reproduce them.
- [Coding Ladder](https://igormcsouza.github.io/tether/ladder/): tether's own coding benchmark, 24 tasks in 6 tiers, and how to run it.
- [Coding Ladder results](https://igormcsouza.github.io/tether/ladder/results/): where qwen3.5:9b, qwen3.5:4b and qwen2.5-coder:7b stop, tether against a bare tool loop, and what to expect.
- [Coding Ladder results, Claude Haiku](https://igormcsouza.github.io/tether/ladder/claude-haiku/): how far Claude Haiku climbs with and without tether, next to qwen3.5:9b, and what limits each.
- [Everyday work ladder, Claude Haiku](https://igormcsouza.github.io/tether/ladder/general/): the non-coding kinds (content, Q&A over documents, critique, extraction to JSON) and how Claude Haiku does on them through tether.
- [Glossary](https://igormcsouza.github.io/tether/glossary/): the terms used across the docs.

## Reference
- [CLI](https://igormcsouza.github.io/tether/reference/cli/): every subcommand, flag and exit code, including `doctor`, `diff`, `export`, `replay`, `--max-tokens`, `--worktree` and `pipeline --resume`.
- [Model providers](https://igormcsouza.github.io/tether/reference/providers/): built-in prefixes, providers.yaml, Python providers.
- [Agent interface](https://igormcsouza.github.io/tether/reference/agent-interface/): JSON shape, exit codes, MCP tools.
- [Harness and CLI (API)](https://igormcsouza.github.io/tether/reference/harness/)
- [Context and SQLite store](https://igormcsouza.github.io/tether/reference/context-and-store/)
- [Multiplexer and decorator](https://igormcsouza.github.io/tether/reference/multiplexer-and-decorator/)
- [Sandbox and skills](https://igormcsouza.github.io/tether/reference/sandbox-and-skills/)
- [Built-in tools (API)](https://igormcsouza.github.io/tether/reference/tools/)

## Help
- [Troubleshooting](https://igormcsouza.github.io/tether/troubleshooting/): by symptom, cause and fix.
- [Release notes](https://igormcsouza.github.io/tether/release-notes/)

## Optional
- [Source and issues](https://github.com/igormcsouza/tether)
- [Contributing](https://github.com/igormcsouza/tether/blob/main/CONTRIBUTING.md)