ratel-ai 0.5.0rc2

Python SDK for Ratel — context engineering platform for AI agents. BM25 tool retrieval, MCP ingestion, framework-neutral capability tools.

ratel-ai

Context engineering for Python agents.

Docs • GitHub • Discord

ratel-ai retrieves the tools and skills relevant to each agent turn instead of sending the full catalog to the model. It bundles Ratel's Rust engine in-process: BM25 by default, with configurable semantic and hybrid retrieval available when needed. The default and local-model paths require no API key, vector database, or service. Installing a published package on a supported prebuilt target also requires no Rust toolchain.

Use ToolCatalog for ranked tools with sync or async handlers and SkillCatalog for ranked Markdown playbooks loaded on demand. Expose search_capabilities_tool, invoke_tool_tool, and get_skill_content_tool so an agent can discover tools and skills, invoke tools, and load full skill instructions. Tools from existing MCP servers can be ingested into the tool catalog with the mcp extra.

Semantic and hybrid retrieval use a configurable embedding model (ADR 0012), set per catalog via the embedding argument: the built-in default, a HuggingFace repo or local directory (in-process), or an OpenAI-compatible endpoint (OpenAI, Ollama, TEI, vLLM).

For semantic or hybrid retrieval, register() folds embedding in: it accepts one tool or a whole batch and embeds on a worker thread, so model loading, HTTP, and inference never block the asyncio loop or hold the GIL — and embedding errors surface right at register():

async def retrieve(tools):
    catalog = ToolCatalog(method="semantic", embedding={"ollama": "nomic-embed-text"})
    await catalog.register(tools)                              # embeds the batch here
    return await catalog.search_async("deploy the service", 5)

register() is async for every method (BM25 too); search() stays synchronous for BM25 only, and search_async() covers all three. To change the endpoint's model or vector dimension, construct a new catalog and re-register.

Install

pip install ratel-ai
# MCP ingestion: pip install 'ratel-ai[mcp]'

Quickstart

Save as quickstart.py, then run python quickstart.py:

import asyncio
from ratel_ai import ExecutableTool, ToolCatalog

async def main():
    catalog = ToolCatalog()
    await catalog.register(
        ExecutableTool(
            id="get_weather",
            name="get_weather",
            description="Get the current weather for a city.",
            input_schema={"properties": {"city": {"type": "string"}}},
            output_schema={"type": "object"},
            execute=lambda args: {"forecast": f"Sunny in {args['city']}"},
        )
    )

    hit = catalog.search("What is the weather in Rome?", 1)[0]
    print(await catalog.invoke(hit.tool_id, {"city": "Rome"}))


asyncio.run(main())

Continue with the Python guide, capability tools, API reference, or the Pydantic AI example.

Telemetry export is optional. With the otlp extra installed, configure_telemetry() reads RATEL_URL and RATEL_API_KEY, wires the exporter, and returns a shutdown handle. See the telemetry guide.

Package layout: ratel_ai/ is the Python surface, native/ contains the PyO3 binding, and tests/ exercises both. For local development, create .venv with uv, install maturin, pytest, pytest-asyncio, ruff, and mypy, then run .venv/bin/maturin develop and .venv/bin/pytest.