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evalstate/fast-agent

3,780PythonAudience · developerComplexity · 3/5Setup · moderate

TLDR

A Python framework for building and running AI agent apps from the command line, with support for chaining agents, connecting external tools via the Model Context Protocol, and evaluating multi-step workflows.

Mindmap

mindmap
  root((fast-agent))
    What It Does
      Run LLM agents
      Chain workflows
      Evaluate outputs
    Tech Stack
      Python runtime
      MCP protocol
      Ollama local models
    Use Cases
      Coding assistant
      Data analysis
      Multi-agent systems
    Audience
      Developers
      AI app builders
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Things people build with this

USE CASE 1

Build a multi-agent workflow where a coordinator delegates tasks to specialist agents

USE CASE 2

Connect external data sources and tools to your AI app using MCP tool servers

USE CASE 3

Run a coding assistant from the terminal that can execute shell commands and use preconfigured capability packs

USE CASE 4

Evaluate LLM workflows end-to-end with built-in transport diagnostics and OAuth-secured server connections

Tech stack

PythonuvMCPOllamaPyPI

Getting it running

Difficulty · moderate Time to first run · 5min

Requires an API key for a hosted LLM provider such as Anthropic or OpenAI to use cloud models.

In plain English

fast-agent is a Python framework for building, running, and evaluating applications that use large language models. It is designed around a command-line interface with an optional interactive terminal, and it positions itself as a coding assistant, workflow platform, and evaluation tool all in one package. The simplest way to try it is a single terminal command using uv, a Python package runner, which downloads and starts fast-agent without a permanent install. Once running, you can chat with a model, run shell commands by prefixing them with an exclamation mark, attach remote tool servers using the slash-connect command, and install preconfigured capability packs designed for tasks like data analysis or coding. The tool supports local models through Ollama and llama.cpp in addition to hosted providers. On the developer side, defining an agent in Python takes a few lines. You attach a decorator to a function with an instruction string, then call the agent with text input or launch an interactive session. Multiple agents can be composed into workflows using patterns described in the README, such as chains where one agent passes output to the next, or networks where a coordinator agent delegates to specialist agents. Configuration files keep prompts and settings out of the main application code, which makes it easier to version-control and adjust behavior without editing Python. The project claims to be the first framework with complete end-to-end tested support for MCP, the Model Context Protocol that standardizes how AI models connect to external tools and data sources. It also supports MCP Elicitations, which allow a model to ask a human for additional input mid-task. Transport diagnostics are built in, including inspection of Streamable HTTP transport traffic, and OAuth is supported for connecting to secured MCP servers. Model support covers Anthropic, OpenAI, Google, Azure, Deepseek, Ollama, and others. The package is distributed on PyPI and documented on the fast-agent.ai website.

Copy-paste prompts

Prompt 1
Using the fast-agent Python framework, create an agent that chains two steps: first summarizes a text file, then translates the summary into Spanish
Prompt 2
Help me set up a fast-agent workflow with a coordinator agent that routes questions to either a coding specialist or a research specialist agent
Prompt 3
Show me how to connect a remote MCP tool server to a fast-agent app using the slash-connect command and configure it in a settings file
Prompt 4
I want to build a fast-agent app that uses Ollama for local model inference instead of a hosted provider, walk me through the configuration file setup
Prompt 5
Help me write a fast-agent evaluation script that runs a set of test inputs through my agent workflow and scores the outputs
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