ai-agent-gateway 0.5.3

Generic AI agent gateway with MCP tool support and streaming

ai-agent-gateway

Deploy AI agents as production services.

Other frameworks help you define what your agent does. This handles everything around it — the HTTP server, session management, SSE streaming, tool dispatch, human-in-the-loop approval, and code execution sandboxing.

Start with a system prompt. Add MCP tools, local Python tools, skills, and code execution as you need them. Requires Python >= 3.10.

Install + Quick Start

create_agent() is the fastest path to a working agent server. It uses Anthropic by default, and you can switch to OpenAI with provider="openai". Use create_gateway_app() when you need lower-level runtime control.

Install the package and uvicorn:

pip install "ai-agent-gateway[anthropic]" uvicorn
export ANTHROPIC_API_KEY="your-anthropic-api-key"

For OpenAI instead:

pip install "ai-agent-gateway[openai]" uvicorn
export OPENAI_API_KEY="your-openai-api-key"

Create agent.py:

from agent_gateway import create_agent

app = create_agent("You are a concise research assistant.")

Run the server:

uvicorn agent:app --reload --port 8000

Create a session token:

SESSION_TOKEN=$(curl -s http://127.0.0.1:8000/api/chat/init \
  -H 'Content-Type: application/json' \
  -d '{"api_key":"local-demo-key"}' \
  | python3 -c 'import json,sys; print(json.load(sys.stdin)["session_token"])')

Chat with the agent:

curl -N http://127.0.0.1:8000/api/chat \
  -H "Authorization: Bearer $SESSION_TOKEN" \
  -H 'Content-Type: application/json' \
  -d '{"messages": [{"role": "user", "content": "Give me three bullet points on why SSE is useful for chat UIs."}]}'

You will get an SSE stream like:

data: {"type":"text_delta","text":"- SSE lets the server push tokens as they are generated.\n"}

data: {"type":"text_delta","text":"- The browser can render partial output without polling.\n"}

data: {"type":"stream_complete","usage":{"input_tokens":...,"output_tokens":...}}

Full 5-minute walkthrough: Quickstart

Features

• FastAPI server factory with /api/chat/init, /api/chat, /api/chat/tool-result, /api/chat/tool-approval, and /api/health
• SSE event stream for text deltas, thinking deltas, tool calls, approval requests, tool output chunks, retries, and completion
• JWT sessions with scoped approvals and isolated code execution directories
• MCP tool discovery from inline config or ~/.claude.json
• Local Python tool handlers with the same dispatch loop as MCP tools
• Code execution with Docker preferred and subprocess fallback
• Markdown skill files (prompt + config per task) and sub-agents via the built-in run_agent tool
• Anthropic and OpenAI providers through create_agent() or create_gateway_app()
• Headless execution via run_autonomous() for cron jobs and batch agents — same tool/MCP/skill infrastructure, no HTTP server
• Heartbeat loop via HeartbeatLoop for persistent agents that check in periodically with quiet suppression, active hours, and backoff

You bring your system prompt, your tools (MCP servers, local Python handlers, or both), and your runtime policy. The gateway handles everything else.

Progressive Examples

Tier 1: System Prompt Only

from agent_gateway import create_agent

app = create_agent("You are a helpful assistant for spreadsheet users.")

Tier 2: Add MCP Tools

This uses an inline MCP server config. The example below assumes Node.js is installed because it runs an npx-based MCP server.

from agent_gateway import create_agent

app = create_agent(
  "You can inspect and edit files when needed.",
  mcp_servers={
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "."],
    }
  },
)

Tier 3: Add Local Tools

from agent_gateway import create_agent


async def summarize_csv(tool_input, **_kwargs):
  path = tool_input["path"]
  return {"summary": f"Would summarize {path}"}, None


app = create_agent(
  "Use the summarize_csv tool when the user asks for a file summary.",
  tool_handlers={"summarize_csv": summarize_csv},
  tool_definitions=[
    {
      "name": "summarize_csv",
      "description": "Summarize a CSV file on disk.",
      "input_schema": {
        "type": "object",
        "properties": {
          "path": {"type": "string", "description": "Path to the CSV file."}
        },
        "required": ["path"],
      },
    }
  ],
)

Tier 4: Add Code Execution and Skills

code_execution=True prefers Docker when available and falls back to local subprocess execution otherwise.

from agent_gateway import create_agent

app = create_agent(
  "Use code execution for calculations and run_agent for focused subtasks.",
  code_execution=True,       # Adds code_execute tool (Docker preferred, subprocess fallback)
  skills_dir="skills",       # Each .md file becomes a named skill for run_agent
)

Tier 5: Headless / Autonomous

Run the same agent loop without an HTTP server — for cron jobs, batch tasks, or persistent daemons.

from agent_gateway import run_autonomous_sync, DeliveryConfig

result = run_autonomous_sync(
  "You are an operations monitor. Call check_status before replying.",
  "Check the current status and send a summary.",
  tool_handlers={"check_status": check_status},
  tool_definitions=[...],
  state_dir="./state",
  delivery=DeliveryConfig(telegram_bot_token="...", telegram_chat_id="..."),
)

For persistent agents that check in periodically, wrap with HeartbeatLoop:

from functools import partial
from agent_gateway import run_autonomous, HeartbeatLoop, HeartbeatConfig

loop = HeartbeatLoop(
  run_fn=partial(run_autonomous, system_prompt="...", initial_message="...", ...),
  config=HeartbeatConfig(interval_seconds=1800, active_hours=(6, 22), timezone="America/New_York"),
  on_alert=my_delivery_callback,  # called only when agent has something to report
)
await loop.start()

Graduate: Switch to create_gateway_app()

Use create_gateway_app() when you need custom approval logic, channel-aware runtimes, interceptors, multiple runtime profiles, or deeper production hooks.

from agent_gateway import (
  AnthropicProvider, ChatRuntime, GatewayServerConfig, create_gateway_app,
)

# Full control: custom providers, approval logic, channel routing, interceptors.
# See examples/07-full-production/ for the complete version.
app = create_gateway_app(
  GatewayServerConfig(
    build_chat_runtime=my_runtime_factory,
    default_provider=AnthropicProvider(),
  )
)

Runnable versions of these examples live in examples/.

Architecture

Three entry points share the same agent core:

create_agent()         --> FastAPI HTTP server (interactive chat)
run_autonomous()       --> Headless one-shot (cron / batch)
HeartbeatLoop          --> Persistent daemon (periodic check-in)
        |
        v
    AgentRunner (model loop: stream -> tool calls -> dispatch -> resume)
        |
        v
    ToolDispatcher
        |-- interceptors (rate limits, custom policies)
        |-- approval check (session-scoped, HTTP only)
        |-- local Python handler
        |-- MCP server (stdio)
        |-- code_execute (Docker / subprocess)
        |-- run_agent (sub-agent with own runner)
        |
        v
    EventLog --> SSE events (HTTP) or RunOutput (autonomous)

The same backend can serve multiple frontends. Pass context.channel to shape runtime behavior per client without rewriting the agent loop.

Comparison

Category	ai-agent-gateway	LangGraph	LangChain	CrewAI	mcp-agent
Primary purpose	Deploying agents as services	Stateful workflow graphs	LLM app building blocks	Multi-agent role/task orchestration	MCP-centric workflow orchestration
Agent logic	Model-driven prompts with tools	Code-defined graph nodes and edges	Code-defined chains and agents	Code-defined crews and tasks	Code-defined workflows
Tool system	MCP-native plus local handlers	Bring your own adapters	Bring your own adapters	Custom tool abstractions	MCP-native
Server/runtime	FastAPI + SSE in core	Bring your own or LangGraph Platform	LangServe is separate	Bring your own	Bring your own
Sessions/auth	JWT sessions in core	Bring your own	Bring your own	Bring your own	Bring your own
Human approval	Built into tool dispatch	Available through interrupt/checkpoint patterns	Not a core runtime feature	Human-input patterns available	Not a core runtime feature
Best for	Shipping a chat-facing agent backend quickly	Explicit workflow control flow	Reusable LLM components	Team-style agent simulations	MCP-heavy automation flows

When to use this package: you want users or clients talking to an agent over HTTP, and you do not want to build the session, SSE, approval, and tool-serving infrastructure yourself.

When not to use this package: you want explicit graph orchestration, or you are building a one-off notebook or script that does not need a reusable server runtime.

You can also combine them. For example, a LangGraph workflow can sit behind an ai-agent-gateway HTTP surface.

Documentation

• Quickstart
• HTTP API
• Architecture
• Comparison
• API Reference
• Contributing

License

MIT