Tool Selection
~3 min read
Concept & How It Works
Why Does It Exist?
Too many tools confuse the LLM (tool overload). Too few limit capability. Smart selection balances coverage with precision.
Real-World Analogy
Tool selection is a chef choosing knives — the right tool for the task, not every knife on the rack for slicing a tomato.
Visual Workflows
What is Tool Selection?
Example
Scenario
Given 50 registered tools, an embedding router selects the 8 most relevant for 'generate a sales report from our CRM' before the LLM call.
Solution
In Tool Calling & Function Calling, apply Tool Selection to this scenario: Given 50 registered tools, an embedding router selects the 8 most relevant for 'generate a sales report from our CRM' before the LLM call. Identify the inputs, run the technique, validate the output, and note one thing you would monitor in production.
Practice Task
Do this before moving to the next module — reading alone is not enough.
Open the Code Walkthrough below and run it locally. Change one parameter related to Tool Selection (e.g. model, temperature, top_k, or tool name), observe the difference in output, and write 2–3 sentences explaining what changed.
Code Walkthrough
Highlighted lines show where Tool Selection happens in the code.
1# Tool Selection — minimal example2from openai import OpenAI3
4client = OpenAI() # create API client5
6# Ask the model to explain this topic7response = client.chat.completions.create( # core API call for Tool Selection8 model="gpt-4o-mini",9 messages=[10 {"role": "system", "content": "You explain tool selection clearly."},11 {"role": "user", "content": f"What is tool selection?"},12 ],13 temperature=0,14)15print(response.choices[0].message.content) # show output for debuggingCommands to Remember
Commands to Remember
client.chat.completions.create(..., tools=[...]) # pass tool schemas to APIjson.loads(response.choices[0].message.tool_calls[0].function.arguments) # parse tool argspip install pydantic # validate tool inputs with schemas
Common Mistakes
- Treating Tool Selection as a black box without evaluation
- Ignoring cost and latency in production
- Skipping error handling for tool selection
Cheat Sheet
Quick recap — the most important points from this module.
Cheat Sheet
quick ref- •Tool Selection
- •Tool Overload
- •Router Model
- •Embedding Retrieval