[](https://pypi.org/project/agentor/)
[](https://github.com/CelestoAI/agentor/actions/workflows/test.yml)
[](https://opensource.org/licenses/Apache-2.0)
Fastest way to build and deploy long-running AI agentsβwith durability, observability, and security.
Docs |
Examples
## Features
| Feature | Description | Docs
|---------------------------|------------------------------------------|-----------------------|
| π MCP & tool security | The only **full FastAPI compatible** MCP Server with decorator API | [Link](https://docs.celesto.ai/agentor/tools/LiteMCP)
| π¦Ύ Agent-to-agent | Multi-agent communication | [Link](https://docs.celesto.ai/agentor/agent-to-agent)
| π Observability | Agent tracing and monitoring | [Link](https://celesto.ai)
| πΎ Durable runs | Persist, resume, and fork agent runs | [Durable runs docs](https://docs.celesto.ai/agentor)
| π Tool Search API | Reduced tool context bloat | [Link](https://docs.celesto.ai/agentor/tools/tool-search)
## π
Quick Start
### Installation
The recommended method of installing `agentor` is with pip from PyPI.
```bash
pip install agentor
```
This installs the v0.1.0 line, built on Agentor's own agent engine β durable,
forkable runs included.
Tools with heavy or vendor-specific dependencies ship as extras, so the base
install stays small:
```bash
pip install "agentor[google]" # GmailTool, CalendarTool
pip install "agentor[all]" # every optional tool
```
Available extras: `google`, `exa`, `git`, `github`, `slack`, `postgres`, `scrapegraph`, `all`.
More ways...
You can also install the latest bleeding edge version (could be unstable) of `agentor`, should you feel motivated enough, as follows:
```bash
pip install git+https://github.com/celestoai/agentor@main
```
## Build and Serve an Agent
Build an Agent, connect external tools or MCP Server and serve as an API in just a few lines of code:
```python
from agentor.tools import GetWeatherTool
from agentor import Agentor
agent = Agentor(
name="Weather Agent",
model="gpt-5-mini", # Use any LLM provider - gemini/gemini-2.5-pro or anthropic/claude-3.5
tools=[GetWeatherTool()]
)
result = agent.run("What is the weather in London?") # Run the Agent
print(result)
# Serve Agent with a single line of code
agent.serve()
```
### Any OpenAI-compatible provider
Point `base_url` at any provider that speaks OpenAI's `/chat/completions` β OpenRouter,
Groq, Together, Fireworks, DeepSeek, vLLM, Ollama, or Anthropic's and Gemini's compatible
endpoints β with no extra dependency:
```python
agent = Agentor(
name="Assistant",
model="openrouter/auto",
base_url="https://openrouter.ai/api/v1",
api_key=os.environ["OPENROUTER_API_KEY"],
)
```
Run the following command to query the Agent server:
```bash
curl -X 'POST' \
'http://localhost:8000/chat' \
-H 'accept: application/json' \
-H 'Content-Type: application/json' \
-d '{
"input": "What is the weather in London?"
}'
```
`agent.serve()` gives you an ordinary ASGI app, so host it wherever you already
run Python services.
## Durable Runs
Give the agent a store and every run becomes an append-only event log that
survives process death. Resume an interrupted run, or fork any persisted run β
even a completed one β into a new, independent run that keeps the full trace,
the model's reasoning included when the provider returns it:
```python
from agentor import Agentor
from agentor.engine.store import FileStore
agent = Agentor(name="Assistant", model="gpt-5-mini", store=FileStore("runs"))
result = agent.run("Draft a launch plan") # persisted under result.run_id
# Interrupted mid-run? agent.resume(result.run_id) picks up where it left off.
fork = agent.fork(result.run_id, "Make it punchier") # fork.run_id is a new run; parent untouched
```
`fork` and `resume` have async twins, `afork` and `aresume`.
## Tracing
Tracing is **off unless you ask for it**. A trace carries prompts, tool arguments, tool
results, and the model's reasoning when a provider returns it β so nothing leaves your
process by default.
Turn it on for an agent:
```python
agent = Agentor(name="Assistant", enable_tracing=True) # needs CELESTO_API_KEY
```
Or decide per run:
```python
agent.run("public question")
agent.run("contains customer data", tracing=False) # this run sends nothing
agent.run("debug this", tracing=True) # trace just this one
```
`tracing=` is accepted by `run`, `arun`, `chat` and `stream_chat`. View traces at
[celesto.ai/observe](https://celesto.ai/observe).
## Agent Skills
Skills are folders of instructions, scripts, and resources that Claude loads dynamically to improve performance on specialized tasks.
Agent Skills help agents pull just the right context from simple Markdown files. The agent first sees only a skillβs name and short description. When the task matches, it loads the rest of `SKILL.md`, follows the steps, and can call a shell environment to run the commands the skill points to.
- **Starts light**: discover skills by name/description only
- **Loads on demand**: pull full instructions from `SKILL.md` when relevant
- **Executes safely**: run skill-driven commands in an isolated shell
Skill layout example:
```
example-skill/
βββ SKILL.md # required instructions + metadata
βββ scripts/ # optional helpers the agent can call
βββ assets/ # optional templates/resources
βββ references/ # optional docs or checklists
```
Using a skill to create a GIF:
```python
from agentor.tools import ShellTool
from agentor import Agentor
agent = Agentor(
name="Assistant",
model="gemini/gemini-3-flash-preview",
instructions="Your job is to create GIFs. Lean on the shell tool and any available skills.",
skills=[".skills/slack-gif-creator"],
tools=[ShellTool()],
)
async for chunk in await agent.chat("produce a cat gif", stream=True):
print(chunk)
```
## Create an Agent from Markdown
Bootstrap an Agent directly from a markdown file with metadata for name, tools, model, and temperature:
```markdown
---
name: WeatherBot
tools: [get_weather]
model: gpt-4o-mini
temperature: 0.3
---
You are a concise weather assistant.
```
Load it with:
```python
from agentor import Agentor
agent = Agentor.from_md("agent.md")
result = agent.run("Weather in Paris?")
```
## Build a custom MCP Server with LiteMCP
Agentor enables you to build a custom [MCP Server](https://modelcontextprotocol.io) using LiteMCP. You can run it inside a FastAPI application or as a standalone MCP server.
Agentor uses the official MCP Python SDK 2.3 or newer within the 2.x line.
FastMCP is not an Agentor dependency; the LiteMCP decorator API is unchanged.
```python
from agentor.mcp import LiteMCP, get_token
mcp = LiteMCP(name="my-server", version="1.0.0")
@mcp.tool(description="Get weather for a given location")
def get_weather(location: str) -> str:
# *********** Control authentication ***********
token = get_token()
if token != "SOME_SECRET":
return "Not authorized"
return f"Weather in {location}: Sunny, 72Β°F"
mcp.serve()
```
### LiteMCP vs FastMCP
**Key Difference:** LiteMCP is a native ASGI app that integrates directly with FastAPI using standard patterns. FastMCP requires mounting as a sub-application, diverging from standard FastAPI primitives.
| Feature | LiteMCP | FastMCP |
|---------|---------|---------|
| Integration | Native ASGI | Requires mounting |
| FastAPI Patterns | β
Standard | β οΈ Diverges |
| Built-in CORS | β
| β |
| Custom Methods | β
Full | β οΈ Limited |
| With Existing Backend | β
Easy | β οΈ Complex |
π [Learn more](https://docs.celesto.ai/agentor/tools/LiteMCP)
## Connect an Agent to an MCP Server
Use `MCPServer` for a remote server that supports Streamable HTTP. Agentor
discovers its tools, including paginated results, and closes the connection
after the run:
```python
from agentor import Agentor
from agentor.mcp import MCPServer
agent = Agentor(
name="Assistant",
model="gpt-5-mini",
tools=[MCPServer(url="https://your-server.example/mcp")],
)
```
Hosts that supply their own HTTP transport can pass `http_client_factory` to
`MCPServer`. The factory receives `headers` and `timeout` keyword arguments and
must return a new `httpx2.AsyncClient`. Agentor owns that client's lifecycle,
closing it when connection setup fails or the MCP connection closes.
### Search the web through MCP
The [Parallel Search example](examples/parallel_search.md) connects an agent to
web search and page extraction without a Parallel API key. It also includes a
tools-only mode that runs without model credentials:
```bash
uv run python examples/parallel_search.py --tools-only "Agentor durable agent runs"
```
## Agent-to-Agent (A2A) Protocol
The A2A Protocol defines standard specifications for agent communication and message formatting, enabling seamless interoperability between different AI agents.
**Key Features:**
- **Standard Communication**: JSON-RPC based messaging with support for both streaming and non-streaming responses
- **Agent Discovery**: Automatic agent card generation at `/.well-known/agent-card.json` describing agent capabilities, skills, and endpoints
- **Rich Interactions**: Built-in support for tasks, status updates, and artifact sharing between agents
Agentor makes it easy to serve any agent as an A2A protocol.
```python
from agentor import Agentor
agent = Agentor(
name="Weather Agent",
model="gpt-5-mini",
tools=["get_weather"],
)
# Serve agent with A2A protocol enabled automatically
agent.serve(port=8000)
# Agent card available at: http://localhost:8000/.well-known/agent-card.json
```
Any agent served with `agent.serve()` automatically becomes A2A-compatible with standardized endpoints for message sending, streaming, and task management.
π [Learn more](https://docs.celesto.ai/agentor/agent-to-agent)
## π€ Contributing
We'd love your help making Agentor even better! Please read our [Contributing Guidelines](.github/CONTRIBUTING.md) and [Code of Conduct](.github/CODE_OF_CONDUCT.md).
## π License
Apache 2.0 License - see [LICENSE](LICENSE) for details.
---