justin dd691b0111 rag: cap chunk size at 6KB to fit nomic-embed-text 2048-tok context
The chunker emits any single paragraph as a stand-alone chunk regardless
of size. One HVM page had a 14,858-char paragraph (a big config table) —
nomic-embed-text 400'd the entire embed batch because the model's context
is 2048 tokens. Added a hard-split fallback that splits any oversized
chunk on line boundaries to MAX_CHARS=6000 (~1500 tokens, headroom).

Also defaulted PRODUCT_NAME to "hvm" in rag/index.py to match server.py.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-22 13:06:35 -04:00

docs-mcp-template

A reusable template for building hosted MCP servers over a product's public documentation. Distilled from one production build; everything product-specific has been factored out.

The end product is a streamable-HTTP MCP server with ~15 tools that any LLM client (Claude Desktop, Claude Code, Cursor, Copilot) can call to answer questions against the docs, surface what changed recently, find inconsistencies, and (optionally) submit doc bugs back upstream.

What's here

  • PLAN.md — comprehensive build guide. Phased approach (13 phases, ~23 weeks of focused work for the full stack). Includes the design decisions, the gotchas, and a per-product customization checklist.
  • Scaffolded skeleton — working FastMCP server with stub tools, Dockerfile, docker-compose, CI workflows, eval harness layout, usage logging. Everything you need to git clone and start filling in the product-specific bits.

Quick start

git clone https://git.jpaul.io/justin/docs-mcp-template.git my-product-docs
cd my-product-docs
git remote remove origin  # detach from template
python -m venv venv && source venv/bin/activate
pip install -r requirements.txt

# Read PLAN.md before doing anything else. Pay particular attention to
# Phase 1 (scraper) — that's the most product-specific phase.

# Run the stub server (no corpus yet — just verifies the wiring):
python -m docs_mcp.server --transport stdio

Repo layout

.
├── PLAN.md                        # The build guide. Read first.
├── README.md
├── requirements.txt
├── Dockerfile
├── .gitignore
├── .gitea/workflows/
│   ├── refresh.yml                # Weekly scrape + index + image push
│   └── image-only.yml             # On-demand code-only ship
├── scrape/
│   ├── README.md                  # Product-specific scraper goes here
│   └── changelog.py               # Reusable: --json, --history-out
├── rag/
│   ├── embeddings.py              # Ollama embedder, swappable
│   ├── chunk.py                   # Chunker — adjust per page format
│   ├── index.py                   # Builds Chroma + (optionally) BM25
│   └── bm25.py                    # SQLite FTS5 lexical index
├── docs_mcp/
│   ├── server.py                  # FastMCP server with stub tools
│   └── usage.py                   # TimedCall + JSONL telemetry
├── eval/
│   ├── queries.jsonl.example      # Curate ~25 hand-labeled queries
│   ├── retrievers.py              # Retriever protocol + implementations
│   └── run_eval.py                # MRR / Recall@k / nDCG@k harness
├── scripts/
│   ├── usage_report.py            # Standalone log analyzer
│   └── registry_gc.py             # Container registry cleanup
└── deploy/
    └── docker-compose.yml         # Hosting stack: MCP + reranker + Watchtower

What's product-specific (must implement)

  • scrape/ — the scraper itself. The template gives you the corpus layout contract and a working changelog.py; the actual extraction logic is yours.
  • The corpus on disk (gitignored; rebuilt by CI).
  • The reranker GGUF model and llama.cpp container (commented in deploy/docker-compose.yml).
  • The reverse proxy / TLS layer in front of the public endpoint.
  • The hand-curated knowledge surface (your product's API gotchas, example scripts, anything the LLM should know that the docs don't say).

What's NOT product-specific (works as-is)

  • FastMCP server skeleton + tool decoration pattern
  • Chroma + Ollama embedding pipeline
  • BM25 / SQLite FTS5 lexical index
  • Hybrid retrieval (RRF) + reranker integration
  • Eval harness (Retriever protocol, MRR/Recall/nDCG)
  • Usage logging (TimedCall, JSONL, daily rotation)
  • CI workflow shape (weekly + on-demand, retry-on-race, three-tag image scheme)
  • Registry GC script
  • Standard tools: search_docs, get_page, list_versions, diff_versions, bundle_changelog, weekly_digest, find_doc_inconsistencies, submit_doc_bug, etc.

License

Internal template. Adjust before publishing.

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