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The KnowledgeToolkit provides agents with tools to search a knowledge base on demand. Unlike the automatic KnowledgeMiddleware (which retrieves context before every model call), the toolkit lets the agent decide when to search.

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When to Use

ApproachHow It WorksBest For
KnowledgeMiddlewareAutomatically retrieves context on every turnAlways-on RAG, simple Q&A
KnowledgeToolkitAgent calls search_knowledge when it decides toSelective retrieval, multi-step reasoning
Use KnowledgeToolkit when:
  • The agent should decide whether a search is needed
  • Not every user message requires knowledge retrieval
  • The agent needs to search multiple times with different queries

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Setup

from definable.agents import Agent
from definable.agents.toolkits import KnowledgeToolkit
from definable.knowledge import Knowledge, InMemoryVectorDB, OpenAIEmbedder
from definable.models import OpenAIChat

# Build a knowledge base
knowledge = Knowledge(
    vector_db=InMemoryVectorDB(),
    embedder=OpenAIEmbedder(),
)
knowledge.add("Definable supports OpenAI, DeepSeek, Moonshot, and xAI models.")
knowledge.add("Agents can use tools, middleware, and knowledge bases.")
knowledge.add("The @tool decorator converts functions into agent-callable tools.")

# Create the toolkit
toolkit = KnowledgeToolkit(knowledge=knowledge)

# Use with an agent
agent = Agent(
    model=OpenAIChat(id="gpt-4o"),
    toolkits=[toolkit],
    instructions="You are a documentation assistant. Search the knowledge base when you need specific information.",
)

output = agent.run("What models does Definable support?")
print(output.content)

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Provided Tools

The toolkit exposes two tools to the agent:

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search_knowledge

Searches the knowledge base with a natural language query. 
search_knowledge(query: str, top_k: int = 5) -> str
Returns the most relevant document chunks as formatted text.

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get_document_count

Returns the number of documents in the knowledge base. 
get_document_count() -> str
Useful for the agent to understand the scope of available knowledge.

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Combining with Other Tools

The knowledge toolkit works alongside other tools: 
@tool
def get_current_date() -> str:
    """Get today's date."""
    from datetime import date
    return str(date.today())

agent = Agent(
    model=OpenAIChat(id="gpt-4o"),
    tools=[get_current_date],
    toolkits=[KnowledgeToolkit(knowledge=knowledge)],
)
The agent can call search_knowledge to find information and get_current_date for context, combining results in its response.
For a fully automatic approach where the agent doesn’t need to decide when to search, see KnowledgeMiddleware instead.