fastcontext-hybrid-mcp
Allows the Hermes agent to use FastContext for codebase exploration.
This server does not currently have a deployable release on Glama. Follow the repository's setup instructions to install and configure it for your MCP client, including any required credentials and local dependencies.
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 synthesisPerformance 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 contextWhat 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)
Quick Start (macOS — Recommended)
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/projectThis 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/projectLinux CPU-only (or Docker)
WORK_DIR=/path/to/your/project docker compose up fastcontext-cpuQuick 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-cpuThe 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-vulkanUsing with MCP Clients
Always-on streamable-http server (recommended)
Start a single persistent server that accepts requests for any project:
./start.sh /path/to/default/projectThe 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: 120Make sure llama-server is running first (via ./start.sh or manually).
Docker
WORK_DIR=/path/to/your/project docker compose up fastcontext-cpuThe 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 | conceptread_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 |
|
| Project directory to search |
|
| llama-server URL |
|
| Model path |
| auto-detected | llama-server binary path |
|
| MCP transport: |
|
| MCP server bind host (for SSE/HTTP) |
|
| 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
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
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