Compiler access for agents

Tell your agent to read SKILL.md, then give it access to the installed compiler. The skill describes the language; compiler diagnostics decide whether a particular program checks.

Format, check, evaluate

Install Chelis through Get started. For a standalone program, save the first worked lesson as app.ch in an empty folder. Run:

chelis fmt --inplace app.ch
chelis check app.ch
chelis eval --file app.ch --json

check writes a JSON report to stdout. A successful check has an empty errors array and a score of 1. On failure, inspect each diagnostic's kind, message, and suggestions. Use source locations when present; some errors have none. Read the exit status as well as the report. Warnings and command failures can appear on stderr.

eval --json returns named values in roots. Tensor values carry a shape, element dtype, and hexadecimal element bits. A file containing only function definitions has no evaluated roots: supply inputs and call a function, as the worked lesson does.

Reformat after editing and check again. A clean type check establishes the language's typing rules; it does not establish that the numerical answer is the one you intended. Compare results with known cases, and use property checks for stated requirements.

Work inside a project

Keep the compiler pin in reef.toml. From the project directory, run chelis reef setup, then chelis reef build. Setup installs dependencies recorded in the lockfile; build resolves declared dependencies and checks the package. You do not need a source checkout of each library. The Reef guide explains the manifest and installation commands.

MCP connection

The compiler release tested here, 0.19.1, accepts standard MCP stdio requests. A client that uses an mcpServers configuration can launch it with the following entry. Use the chelis shim installed by chelisup; it must be on the client's PATH.

{
  "mcpServers": {
    "chelis": {
      "command": "chelis",
      "args": [
        "+0.19.1",
        "tide",
        "mcp"
      ]
    }
  }
}

The explicit version selects this toolchain even if the client starts inside a project pinned to another compiler. Install it first with chelisup install 0.19.1. Check that this version supports the project before passing that project's source to it.

A working MCP connection completes initialization, discovers tools, and calls chelis_check with these arguments:

{
  "source_kind": "surf",
  "source": "value = 2.0f32 + 3.0f32\n"
}

Expect isError: false and structuredContent.ok: true. Read the tool's structured diagnostics when isError is true. An empty response or an initialization timeout is a connection failure, not a clean program.

MCP sends one UTF-8 JSON-RPC message per line. Keep server stdout reserved for protocol messages and send logs to stderr. See the MCP stdio transport specification for the client-side requirements.