kitai

Kitai is a short agent framework that aims to implement the core features of Google’s ADK in as simple and concise a way as possible. Read through in one sitting to get a better understanding of how hierarchical agents work under the hood, or adapt and modify it to make a framework that fits your exact use case.

Features

• Hierarchical agents - subagents with automatic transfer tools for navigation
• Simple tools - any function is a tool, no decorators needed
• tool_ctx injection - shared state dict automatically passed to tools that need it
• Instruction templating - system prompts auto-filled from state using {var} syntax
• Narrative casting - prior agent messages are summarised and tagged for clarity
• History filtering - subagents can ignore irrelevant history to preserve context
• Before/after callbacks - hook into the agent loop to skip, modify, or replace calls
• Any LLM provider - built on LiteLLM

Installation

pip install kitai

Quick start

from kitai import Agent, Runner

def mult(a:int, b:int):
    "Multiplies two numbers together"
    return a * b

def save(result:str, tool_ctx):
    "Saves some result passed into storage"
    tool_ctx["final_result"] = result

m = "anthropic/claude-haiku-4-5"
a_saver = Agent(m, name="saver", desc="Saves results into storage.", sp="You receive results from other agents and save them with your tool.", tools=[save])
a_maths = Agent(m, name="math_agent", desc="Is good at doing maths.", sp="Always do maths using tools and always pass to saver to save results.", tools=[mult], subagents=[a_saver])
a_writing = Agent("anthropic/claude-opus-4-6", name="writer", desc="A smart and expensive model to help with writing", sp="You help users with writing")
a_root = Agent(m, name="root", desc="General agent", sp="A general coordinator that delegates to sub agents as needed", subagents=[a_maths])

r = Runner(a_root)
r("What's 259875 * 175825?")
r.state

🔧 transfer_to_agent({“agent_name”: “math_agent”})

🔧 mult({“a”: 259875, “b”: 175825})

Now let me save this result to storage:

🔧 transfer_to_agent({“agent_name”: “saver”})

🔧 save({“result”: “259875 * 175825 = 45692521875”})

{'final_result': '259875 * 175825 = 45692521875'}