Developers love the idea of LLMs that can call your code, but most examples drown in boilerplate or require heavyweight orchestration. In just a few lines you can let Claude on Bedrock trigger a Lambda, update a DynamoDB table, and respond instantly to an API call. This post shows exactly how.
What is Bedrock Function Calling?
Bedrock is Amazon’s managed service that hosts large language models (LLMs) like Claude. Function calling (sometimes called tool use) is a feature where the model can suggest that your program run a specific piece of code – for example, “add a new user”. The model returns a JSON payload that describes the function name and arguments. Your service reads that payload, runs the real function, and then sends the result back to the model so it can continue the conversation.
In plain English: Think of the LLM as a helpful assistant that says, “Hey, could you add this person to the database?” and hands you a sticky note with the details. Your code reads the note, does the work, and tells the assistant “Done”.
Why does this matter? Instead of hard‑coding all possible business logic into prompts, you let the model decide when to invoke real code. This keeps prompts short, makes the system extensible, and gives you auditability – you can log every function call.
