Engine SDK¶
antcrew-engine is the Python library that runs inside your agent code. It is the only component your application imports directly.
What it provides¶
Typed contracts — Python functions that compile to LLM prompts. The function signature defines the input schema and expected output type. If the model returns something that doesn't match, the engine retries automatically.
Provider-agnostic model calls — change "openai:gpt-4o" to "anthropic:claude-opus-5" and nothing else changes. The same @contract function runs on any provider.
TraceLog — every LLM call, tool invocation, retry, and result is written to a structured, append-only log. You can replay any past run exactly, without making new API calls.
HITL checkpoints — hitl_checkpoint() pauses execution and waits for a human to approve before continuing. The review request is sent to antcrew-platform and the human responds from the dashboard.
Hello world¶
from antcrew import Agent, contract
@contract
def summarise(content: str) -> str:
"""Summarise the text in one concise paragraph."""
...
agent = Agent(model="openai:gpt-4o-mini")
result = agent.run(summarise, content="Long document…")
print(result)
No prompt engineering. No JSON parsing. No retry logic. The contract signature is the schema; the docstring is the prompt.
Connecting to the platform¶
To send TraceLog events to antcrew-platform in real time:
from antcrew import Agent
from antcrew.platform import PlatformSink
agent = Agent(
model="anthropic:claude-opus-5",
trace_sink=PlatformSink(
base_url="https://platform.yourcompany.com",
api_key="acw_live_...",
),
)
Every run will appear in the platform dashboard with its full event log, status, and any tickets generated.
Core concepts¶
| Concept | What it is |
|---|---|
@contract |
A Python function that defines an LLM task — signature = schema, docstring = prompt |
Agent |
Executes contracts against a configured model and writes to a TraceLog |
TraceLog |
Append-only record of every token, tool call, and decision in a run |
hitl_checkpoint |
Blocking call that pauses execution for a human to approve |
PlatformSink |
Streams TraceLog events to antcrew-platform in real time |