Skip to main content
Glama
LyuboslavLyubenov

fastcontext-hybrid-mcp

FastContext Hybrid MCP Server

An MCP (Model Context Protocol) server that gathers context from codebases using FastContext-1.0-4B-RL — a 4B parameter model trained by Microsoft for repository exploration.

The server combines LLM-guided code exploration with fuzzy matching to find relevant code snippets for any question about a codebase.

How It Works

User question
    ↓
1. DECOMPOSE — break into sub-questions (code-focused + doc-focused)
    ↓
2. EXPLORE — FastContext 4B model searches the codebase via Grep/Glob/Read
    ↓
3. EXTRACT — fuzzy matching extracts only relevant lines from found files
    ↓
4. GAP-FILL — ripgrep + Levenshtein distance catches what the model missed
    ↓
Snippets (~5K tokens) → fed to larger LLM for synthesis

Performance Gains

Why use this pipeline instead of just asking the model directly?

APPROACH COMPARISON (tested on business-auditor, 1170 files)
═══════════════════════════════════════════════════════════════════════════

Method                          Concept     Answerable   Context/Question
                                Coverage
───────────────────────────────────────────────────────────────────────────
Raw FastContext (no pipeline)   50%         3/6          N/A (model output)
+ Path resolution fix           67%         4/6          N/A
+ Hybrid pipeline (unlimited)   97%         6/6          308K tokens
+ Hybrid pipeline (optimized)   92%         6/6           5K tokens  ← this
───────────────────────────────────────────────────────────────────────────

What each layer adds:

Layer                   What it does                            Gain
──────────────────────────────────────────────────────────────────────
FastContext 4B          Finds relevant files via tool calls     Baseline
Query decomposition     Breaks Q into doc + code sub-questions  +17%
Fuzzy snippet extract   camelCase split + Levenshtein matching  +15%
Gap-fill (ripgrep)      Catches what model missed               +25%
──────────────────────────────────────────────────────────────────────
Total: 50% → 92% concept coverage (+84% improvement)

Context efficiency:

Without optimization:  308K tokens/question  (loads full files)
With optimization:       5K tokens/question  (extracts relevant lines only)
Reduction:               62x smaller context

What this means for the larger LLM:

  • Without pipeline: feed 308K tokens of raw files → exceeds most context windows, expensive

  • With pipeline: feed 5K tokens of targeted snippets → fits easily, cheap, higher quality

The 4B model handles the expensive exploration work (searching, reading, filtering). The larger LLM only sees the distilled evidence — no noise, no irrelevant code.

Key Features

  • Smart search: 4B model decides WHERE to look (not just keyword matching)

  • Fuzzy matching: camelCase splitting, separator normalization, Levenshtein distance

  • Minimal context: extracts only relevant lines, not full files (~5K tokens vs ~300K)

  • Gap-fill: ripgrep safety net catches what the model misses

  • Q4 quantization: runs on 6GB+ VRAM, ~67 tok/s generation


Related MCP server: SRC (Structured Repo Context)

For Metal GPU acceleration on Apple Silicon (M1–M4). No Docker needed.

git clone https://github.com/LyuboslavLyubenov/fastcontext-hybrid-mcp
cd fastcontext-hybrid-mcp
chmod +x setup-mac.sh start.sh

# One-command setup (installs dependencies, builds llama.cpp with Metal, downloads model)
./setup-mac.sh

# Start with your project
./start.sh /path/to/your/project

This uses Metal GPU for ~67 tok/s generation. No Docker required.

Prerequisites: macOS on Apple Silicon, Homebrew. The setup script auto-detects everything and installs what's missing.


Quick Start (Linux)

Linux with Vulkan GPU

git clone https://github.com/LyuboslavLyubenov/fastcontext-hybrid-mcp
cd fastcontext-hybrid-mcp
chmod +x setup.sh start.sh

./setup.sh

# Start with your project
./start.sh /path/to/your/project

Linux CPU-only (or Docker)

WORK_DIR=/path/to/your/project docker compose up fastcontext-cpu

Quick Start (Docker)

Docker handles all dependencies but runs CPU-only on macOS (no GPU passthrough).

macOS / Linux CPU

git clone https://github.com/LyuboslavLyubenov/fastcontext-hybrid-mcp
cd fastcontext-hybrid-mcp

WORK_DIR=/path/to/your/project docker compose up fastcontext-cpu

The MCP server exposes streamable-http on port 8090 for MCP clients to connect.

Linux with Vulkan GPU

WORK_DIR=/path/to/your/project docker compose up fastcontext-vulkan

Using with MCP Clients

Start a single persistent server that accepts requests for any project:

./start.sh /path/to/default/project

The server listens on http://127.0.0.1:8090/mcp with streamable-http transport. Configure your MCP client:

{
  "mcp": {
    "fastcontext": {
      "type": "remote",
      "url": "http://127.0.0.1:8090/mcp",
      "enabled": true
    }
  }
}

The distill tool accepts a work_dir parameter per request, so the same server can search any project without restarting:

distill(question="...", work_dir="/path/to/project-a")
distill(question="...", work_dir="/path/to/project-b")

If work_dir is omitted, the default from startup is used.

Stdio (one project per process)

mcp_servers:
  fastcontext:
    command: "python3"
    args: ["/path/to/fastcontext-hybrid-mcp/mcp_server.py"]
    env:
      FASTCONTEXT_WORK_DIR: "/path/to/your/project"
      FASTCONTEXT_SERVER: "http://127.0.0.1:8080"
    timeout: 120

Make sure llama-server is running first (via ./start.sh or manually).

Docker

WORK_DIR=/path/to/your/project docker compose up fastcontext-cpu

The MCP server listens on port 8090 with streamable-http transport. Configure your MCP client to connect:

{
  "mcp": {
    "fastcontext": {
      "type": "remote",
      "url": "http://localhost:8090/mcp",
      "enabled": true
    }
  }
}

Tools

distill

Main tool — retrieves a grounded answer-package for a question. Deterministic ripgrep retrieval finds anchor definitions; the model only extracts artifacts that are present verbatim in the retrieved regions, and every cited symbol/path is validated against the files.

Args:
  question: str        — The question (conceptual or code-specific)
  work_dir: str        — Path to codebase
  seed: int            — Random seed (default: 42)
  max_anchors: int     — Max anchor files to gather evidence from (default: 4)
  evidence_chars: int  — Char budget for gathered evidence (default: 8000)

Returns:
  JSON with:
    answer: str               — Grounded answer citing file:line (when model cooperates)
    artifacts: list           — Verified symbols/values with file + line ranges
    evidence: list            — File:line + actual code region for each anchor
    confidence: str           — high | low | none
    ungrounded_dropped: list  — Model claims that failed validation
    identifiers_used: list    — Identifiers resolved from the question
    identifier_source: str    — literal | concept

read_snippet

Extract relevant lines from a single file using fuzzy matching.

Args:
  filepath: str          — Absolute path to file
  concepts: list[str]    — Concepts to search for
  context_lines: int     — Surrounding lines (default: 2)

list_files

List files matching a glob pattern.

health_check

Check if the inference server is running.


Environment Variables

Variable

Default

Description

FASTCONTEXT_WORK_DIR

/home/llmbox/fastcontext-eval

Project directory to search

FASTCONTEXT_SERVER

http://127.0.0.1:8080

llama-server URL

FASTCONTEXT_MODEL

models/FastContext-1.0-4B-RL-Q4_K_M.gguf

Model path

FASTCONTEXT_LLAMA_CPP

auto-detected

llama-server binary path

FASTCONTEXT_TRANSPORT

stdio

MCP transport: stdio, streamable-http, http, sse (sse deprecated — use streamable-http for network)

FASTCONTEXT_MCP_HOST

0.0.0.0

MCP server bind host (for SSE/HTTP)

FASTCONTEXT_MCP_PORT

8090

MCP server port (for SSE/HTTP)

Hardware Requirements

Backend

Min RAM

GPU

Platform

Notes

Metal

8 GB unified

Apple Silicon M1+

macOS native

Best for macOS — requires native install, not Docker

Vulkan

6 GB

AMD/Intel/NVIDIA

Linux

Mesa or proprietary drivers

CPU

8 GB RAM

None

Any

Works in Docker on any platform, ~10x slower

Performance

Metric

Value

Model size (Q4_K_M)

2.4 GB

VRAM usage

~6 GB (model + KV cache)

Prompt eval

~420 tokens/sec

Generation

~67 tokens/sec

Context per question

~5K tokens

Time per question

~20-40 seconds

Hosting

For team/production deployment, see HOSTING.md:

  • VPS with GPU (Lambda Labs, Vast.ai, RunPod, Hetzner)

  • Systemd services for auto-start

  • Reverse proxy (nginx, Caddy) for network access

  • Docker with persistent model volumes

  • Multi-project setup

  • Cost estimates

License

MIT

A
license - permissive license
-
quality - not tested
B
maintenance

Maintenance

Maintainers
Response time
Release cycle
Releases (12mo)
Commit activity

Resources

Unclaimed servers have limited discoverability.

Looking for Admin?

If you are the server author, to access and configure the admin panel.

Latest Blog Posts

MCP directory API

We provide all the information about MCP servers via our MCP API.

curl -X GET 'https://glama.ai/api/mcp/v1/servers/LyuboslavLyubenov/fastcontext-hybrid-mcp'

If you have feedback or need assistance with the MCP directory API, please join our Discord server