DevOnBike.Overfit.Mcp 10.0.29

DevOnBike.Overfit.Mcp

An MCP (Model Context Protocol) server for the Overfit in-process LLM runtime — dependency-free JSON-RPC 2.0 over stdio, with typed wire contracts (Protocol/) serialized through a source-generated JsonSerializerContext (no SDK, no reflection, no DI), so it drops cleanly into a Native-AOT single binary (AOT-verified end-to-end). Plug local, zero-egress AI tools into any MCP host: Claude Code, Claude Desktop, IDEs.

What you get

• McpServer — a minimal stdio MCP server (initialize / ping / tools/list / tools/call, newline-delimited JSON-RPC, logs on stderr). Requests are served one at a time (single-tenant model session underneath — same stance as the OpenAI server).
• McpTool — name + description + raw JSON Schema + a Func<JsonElement?, McpToolResult> handler. Tool-execution failures flow back as isError results (so the host model can self-correct), never as protocol errors.
• Protocol/ — the typed JSON-RPC/MCP wire contracts (JsonRpcRequest, JsonRpcResponse<T>, McpInitializeResult, McpToolsListResult, McpCallToolResult, …) with a source-generated McpJsonContext : JsonSerializerContext: compile-time serializers, no reflection, every closed JsonRpcResponse<T> registered explicitly. JsonElement is used only where the JSON is genuinely dynamic (the echoed id, params/arguments, inputSchema). The same contracts will serve the future MCP client (host role) — the framing is symmetric.
• OverfitMcpTools — factories for the built-in tools backed by the Overfit runtime:
  • ask — prompt → a local GGUF chat model (Qwen / Llama / Phi / Gemma / Mistral / Bielik …)
  • rag_query — question → answer with citations over a private, locally-indexed document folder
  • transcribe — WAV/MP3 file → text via Whisper, pure C# on the CPU

Usage

using DevOnBike.Overfit.LanguageModels;
using DevOnBike.Overfit.Mcp;

using var client = OverfitClient.LoadGguf(@"C:\models\qwen2.5-3b-instruct-q4_k_m.gguf");

var tools = new[] { OverfitMcpTools.CreateAsk(client) };
var server = new McpServer("overfit", "10.0.23", tools, log: Console.Error);
server.Run(Console.In, Console.Out);   // blocks until the host closes stdin

This is exactly what the overfit mcp CLI command runs. Register it with an MCP host, e.g. Claude Code:

claude mcp add overfit -- overfit mcp C:\models\model.gguf

Or use the helper scripts next to this README: mcp-register.cmd / mcp-unregister.cmd / mcp-status.cmd / mcp-run.cmd (foreground debug) / mcp-smoke.cmd (no-Claude handshake test).

No .NET on the machine? Use the Docker image (devonbikeit/overfit:mcp, ~34 MB, stdio piped via docker run -i): mcp-register-docker.cmd / mcp-smoke-docker.cmd. See docs/mcp.md.

Notes

• stdio transport only (local process = on-brand zero egress). The protocol layer is host-agnostic — an HTTP transport can reuse it.
• Everything stays on your machine: the model, the documents, the audio. No keys, no egress.
• Validated three ways: 12 model-free protocol tests, end-to-end over stdio against the real CLI binary, and inside real Claude Code (✔ Connected + a live session driving all three tools — including a Polish RAG question, confirming the chat-model embeddings are multilingual). Details and the PowerShell -- gotcha: docs/mcp.md.

License

Dual-licensed: AGPL-3.0-or-later for open source; a commercial license is available for closed-source / SaaS / regulated use — see COMMERCIAL.md.