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Tanzanite Docs

The Harness

Every agent in Tanzanite is governed by a harness. The harness is the control layer that decides how an agent behaves.

What the harness defines

Section titled “What the harness defines”
  • System prompt — the base instructions every agent starts from.
  • Available tools — which tools the agent can call, organized into tiers so the agent discovers more capabilities as a task requires them.
  • Model routing — which model handles which kind of step.
  • Safety guardrails — what requires approval and what is blocked.

Part of the platform

Section titled “Part of the platform”

The harness ships with the platform: changes to it are made by the Tanzanite team and reach every agent with a platform release.

Skills and plugins

Section titled “Skills and plugins”

The harness works alongside:

  • Skills — packs of instructions an agent loads for specific tasks. You keep your own library and attach skills to a project (every chat in it) or to a single chat. See Add a skill.
  • Plugins — installable bundles that extend the platform with new tools and integrations.

Attached skills are cheap by design: an agent carries only each skill’s name and description until it judges one relevant, and reads the full instructions only then. That is why the description is the part worth writing carefully — it is what that judgement is made on.

The on-device harness (Local projects)

Section titled “The on-device harness (Local projects)”

For fully private use, a Local project runs its own harness on your machine against an on-device model, so sensitive work — files, prompts and chats alike — never leaves it. See the three setups.

Next steps

Section titled “Next steps”