Find Expert AI Trainers for Function Calling
Post a job and connect with specialists who can create tool-use training data, label correct function calls, and evaluate whether your agents select the right tools with valid arguments. Our network includes 100,000+ AI training specialists.
One place to find AI Trainers who understand tool-use workflows and can deliver schema-valid training data.
Technical Vetting
Pre-screened for structured outputs, schema accuracy, and agent workflow experience
Any Stack
Work in your agent framework, eval platform, or custom tooling
Domain Expertise
Real experience with APIs in finance, healthcare, e-commerce, and more
Hire for Any Function Calling Tool
Have your own tooling? Our talent works directly in your platform.
Pre-Vetted Experts
Countries
Languages
How OpenTrain Works for Function Calling
Post a Job and Receive Pre-Vetted Proposals
Describe your tools, schemas, and workflow requirements. Receive proposals from AI Trainers who have already been screened for structured output work and agent experience.
Hire and Add to Your Tooling
Review candidates, make your hires, and invite them to your agent framework, eval platform, or custom tooling.
Communicate and Pay in One Place
Share instructions, message your team, and handle global payments from a single dashboard.
Start Building Your Function Calling Team Today
Post your first job and connect with pre-vetted AI Trainers who have the structured output experience and technical depth your project requires.
Post Your Function Calling Job
Describe your requirements and receive a curated shortlist of domain experts matched to your project. 15% flat fee, no hidden markups.
Full-Service, End-to-End
- Recruiting & live vetting
- Onboarding & training
- Daily management & QA
- Dedicated program lead
Build a career training the world's top AI models.
Freelance AI Trainer?
Join 127,000+ freelancers
Data Labeling Company?
Find clients and recruit talent
The #1 Talent Network for Function Calling
Tool selection, argument validation, multi-step orchestration, error recovery — whatever your agent architecture requires, we have specialists who've built and evaluated real tool-use systems.
FAQs About Hiring for Function Calling
Common questions about hiring AI Trainers to create function calling training data and evaluate agent tool use.











