Marvin

About

Marvin is a Python framework by PrefectHQ for building agentic AI workflows and producing structured outputs. It allows developers to define Tasks (objective-focused units of work) and assign them to specialized Agents (LLM-powered configurations). Marvin supports type-safe results via Pydantic models, integrates with multiple LLM providers through Pydantic AI, and enables orchestration of multi-agent threads for complex workflows.

Installation

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1) Install Marvin

uv add marvin
# or
pip install marvin

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2) Set your environment variable

macOS / Linux:

export AIML_API_KEY=your-api-key

Windows PowerShell:

setx AIML_API_KEY "your-api-key"

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3) Example — Run an AI/ML API Agent

File: examples/provider_specific/aimlapi/run_agent.py

Python

from __future__ import annotations

import os
from pathlib import Path

from pydantic_ai.models.openai import OpenAIModel
from pydantic_ai.providers.openai import OpenAIProvider

import marvin

AIML_API_URL = "https://api.aimlapi.com/v1"


def get_provider() -> OpenAIProvider:
    api_key = os.getenv("AIML_API_KEY")
    if not api_key:
        raise RuntimeError("Set AIML_API_KEY environment variable to your AI/ML API key.")
    return OpenAIProvider(api_key=api_key, base_url=AIML_API_URL)


def write_file(path: str, content: str) -> None:
    """Write content to a file."""
    Path(path).write_text(content)


def main() -> None:
    writer = marvin.Agent(
        model=OpenAIModel("gpt-4o", provider=get_provider()),
        name="AI/ML Writer",
        instructions="Write concise, engaging content for developers",
        tools=[write_file],
    )

    result = marvin.run(
        "how to use pydantic? write haiku to docs.md",
        agents=[writer],
    )
    print(result)


if __name__ == "__main__":
    main()

Run it:

AIML_API_KEY=your-api-key \
uv run examples/provider_specific/aimlapi/run_agent.py

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4) Other Examples

More examples are available in the same directory:

github.com/PrefectHQ/marvin/tree/main/examples/provider_specific/aimlapi

• structured_output.py — structured JSON output

• tools_agent.py — agent with custom tools (dates, weather)

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Tips

• Profiles: use multiple configurations (default = openai/gpt-5-chat-latest, budget = openai/o4-mini)

• Structured results: pass result_type=... for typed outputs

• Tools: register Python functions via Agent(tools=[...])

• Token limits: increase output size if needed

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Troubleshooting

Issue	Solution
401 Unauthorized	Check your API key and remove extra spaces
404 Model not found	Verify the model ID exists in your account
Network error	Whitelist api.aimlapi.com if behind VPN/proxy

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Helpful Links

• Dashboard

• API Keys

• Model browser

• Docs

• Marvin repository

Enjoy coding with Marvin + AI/ML API 🚀