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The toolchain is not the language. Mzizi is a programming language: its syntax, type system, semantics and contracts. The toolchain is built to support it: to implement it, check it, measure it, and put what Mzizi knows in front of the agents that write it. The harness is the core of Mzizi, and the toolchain attaches to it natively. The harness is the layer an agent reads and works through: the language as an agent sees it (grammar, types, contracts, canonical form), the agent protocol (mz check --agent, its diagnostics and fixes; RFC-0001 §4), and the plugin host that mz, the CLI, the MCP server and plugins attach to. Part of it exists today, in this toolchain, as mz check --agent’s output. The harness as a whole is designed, not built, and the language is writing its RFC. It lives in the language repository, mzizi-dev/mzizi, and the CLI, the MCP server and fundi are its clients. It is not the Phase 0 benchmark harness in benchmarks/harness/, which is the scorer listed below.

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What is in it

mz implements the language, and the benchmark measures it against the best existing language for each kind of task. The rest put the language, its components and its docs within an agent’s reach: the MCP server, the CLI, the skills and the API serve the components (the language’s UI layer) and the doctrine an agent needs to write for them.

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Free, until Fundi

The owner decided on 29 September 2026 that the MCP server and the CLI are free, with no gate. Gating starts at Fundi, which ties into the console at app.mzizi.dev. The Fundi tools (mzizi_fundi, and mzizi_report_issue, which files into the Fundi issue desk) need a signed-in console user. Everything else is served without auth. That is live: on 30 September 2026 an anonymous tools/list on mcp.mzizi.dev/mcp returned all fourteen tools, and calling a Fundi tool without sign-in answered with how to sign in. See the MCP server.

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No database behind any of it

The compiler reads a file and writes to standard output. The benchmark writes results into the repository. The MCP server and the API serve the registry’s files, bundled at build time from a pinned registry commit. None of them has a database. The only database in Mzizi is the console’s. See where data lives.

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Where the source is

mzizi-dev/mzizi and mzizi-dev/mzizi-api-gateway are public. The MCP server, the CLI and the skills bundle are built in a private tooling repository, mzizi-dev/agent-tools, so these docs link their published npm packages rather than their source.