ballast MCP server
Grounds local models with a quantized Wikidata corpus via MCP tools for entity resolution and fact lookup, reducing hallucinations.
README
ballast
Pull a quantized knowledge corpus and ground any local model. Works with Ollama and every OpenAI-compatible or MCP-capable client.
uvx --from git+https://github.com/OpenBallast/ballast-cli openballast pull --level 3
uvx --from git+https://github.com/OpenBallast/ballast-cli openballast serve
(PyPI package coming — it becomes just uvx openballast.)
-
Ollama users: point your client's base URL at
http://localhost:11435/v1instead ofhttp://localhost:11434/v1— done. Every chat request is grounded with corpus facts before your model sees it. No tool calling needed, works with any model size. -
MCP users (Claude Desktop, LM Studio, Cline, Goose): add to your MCP config:
{ "ballast": { "command": "uvx", "args": ["--from", "git+https://github.com/OpenBallast/ballast-cli", "openballast", "mcp"] } } -
Smoke test:
uvx --from git+https://github.com/OpenBallast/ballast-cli openballast lookup "Where was Douglas Adams born?"
What you're downloading
Ballast T0: 25.4M entities and 197M facts from Wikidata (CC0), quantized into nested levels — pick your knowledge size like you pick a GGUF quant:
| level | download | on disk | contains |
|---|---|---|---|
| L0 | 52 MB | 0.2 GB | top 0.5% most notable entities |
| L1 | 92 MB | 0.35 GB | top 1% |
| L2 | 159 MB | 0.6 GB | top 2% |
| L3 | 265 MB | 1.0 GB | top 4% |
| L4 | 427 MB | 1.6 GB | top 8% |
| L5 | 691 MB | 2.6 GB | top 16% |
| L6 | 1.1 GB | 4.2 GB | top 32% |
| L7 | 2.2 GB | 9.2 GB | everything |
Levels are nested: pull --level 5 after pull --level 3 downloads only the
new buckets. Everything runs offline after the pull — no network at answer time.
Measured effect (details: thesis): a 2B model + ~180 MB of ballast exceeds a 12B model's factual accuracy; hallucination on factual probes drops ~3×.
Commands
ballast pull --level 3 # download / upgrade the corpus
ballast serve # OpenAI grounding proxy :11435 + MCP http :11436
ballast mcp # MCP on stdio (for client configs)
ballast lookup "question" # print the evidence blocks for a question
ballast status # installed levels and sizes
BALLAST_HOME overrides the storage location (default ~/.ballast).
How it works
serve intercepts POST /v1/chat/completions, mines entity mentions from your
last message, resolves them against the local corpus (normalized label/alias
match), and prepends the matching facts as a system message. Everything else —
including streaming — passes through untouched. The MCP server exposes the same
three tools (resolve, evidence, lookup) as the hosted demo endpoint
(mcp.openballast.org).
Apache-2.0. Corpus data: CC0 (Wikidata contributors).
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