NPI Review 2026

Overview

Open-source platform for LLM tool-use and function calling

Key Features

• • {'icon': '🔗', 'title': 'Declarative Function Orchestration', 'desc': 'Define tool dependencies and execution order through clean abstractions, eliminating manual coordination logic between sequential function calls in multi-step workflows.'}
• • {'icon': '🛠️', 'title': 'Custom Tool Registration Layer', 'desc': 'Register and compose custom functions as callable tools with typed schemas, enabling LLMs to autonomously invoke domain-specific operations without wrapper boilerplate.'}
• • {'icon': '🔄', 'title': 'Automatic Retry & Error Handling', 'desc': 'Built-in fallback mechanisms and retry logic for failed function calls, allowing agents to recover from transient errors or reformat requests for LLM compatibility.'}
• • {'icon': '📊', 'title': 'Tool Call Tracking & Debugging', 'desc': 'Inspect execution traces showing which tools fired, parameter values, and outputs, enabling developers to audit agent decisions and diagnose tool-calling failures.'}
• • {'icon': '🤖', 'title': 'Multi-Model Function Calling Support', 'desc': "Compatible with multiple LLM providers' function-calling APIs, abstracting protocol differences so agents work consistently across Claude, GPT, Llama, and other models."}

Verdict

NPI is a solid open-source agent tool with 229 GitHub stars. It is worth evaluating against your specific requirements.