Choose the Right AI Model for Your Agent
CustomGPT.ai offers multiple AI models to power your agent. This guide helps you select the best model for your specific needs.
Available Models
This is the summary of models that will help you get the most out of your AI agent:
| Model | Best For | Speed | Availability |
|---|---|---|---|
| GPT-4.1 ⭐ | General use, recommended default | Fast | All plans |
| GPT-6 Sol | High complexity use cases | Moderate | Enterprise |
| GPT-5.6 Sol | High complexity use cases | Slower | Enterprise |
| GPT-5.6 Terra | Premium customer experiences | Moderate | Enterprise |
| GPT-6 Luna | Fast conversational agents | Moderate | Enterprise |
| GPT-5.6 Luna | Fast conversational agents | Moderate | Enterprise |
| GPT-4o mini | High-volume, sub-second responses | Fastest | Premium |
| Claude Opus 5.5 | High complexity use cases | Slower | Enterprise |
| Claude Opus 5 | High complexity use cases | Slower | Enterprise |
| Claude Sonnet 5 Reasoning | When multi-step thinking is required | Slower | Enterprise |
| Claude Sonnet 5 | Premium customer experiences | Moderate | Enterprise |
| Claude Haiku 4.5 | Fast conversational agents | Fast | Enterprise |
| Gemini 3 Pro | Balanced performance + natural dialogue | Moderate | Enterprise |
| Gemini 3.1 Pro | Most use cases | Slower | Enterprise |
| Gemini 3.5 Flash | Fast responses with Google AI | Fast | Enterprise |
For the full list of available models, please check this article: Available AI models and capabilities
GPT-4.1 ⭐ Recommended Default
The best choice for most use cases. GPT-4.1 delivers reliable performance for ticket deflection, internal search, research assistance, and customer engagement.
Recommended for:
- Ticket deflection and customer support agents
- Internal knowledge base search
- Employee onboarding and training assistants
- Research assistants
- Lead engagement and pre-sales support
Start here unless you have a specific reason to choose another model.
Supported agent capabilities: Optimal, Accuracy, Understanding.
GPT-4o mini
Optimized for sub-second response times, at the cost of reduced intelligence.
Recommended for:
- Instant responses (under 1 second)
- Simple lookups and quick conversations
Trade-off: Less sophisticated than GPT-4.1. Not recommended for complex analysis or nuanced conversations. Increases hallucination likelihood.
Supported agent capabilities: Speed.
GPT-6 Sol
OpenAI's GPT-6 Sol and GPT-6 Luna "bring frontier intelligence to everyday work with different balances of capability and cost."
Recommended for:
- High complexity use cases
Supported agent capabilities: Optimal, Accuracy, Understanding.
GPT-6 Luna
OpenAI's GPT-6 Sol and GPT-6 Luna "bring frontier intelligence to everyday work with different balances of capability and cost."
Recommended for:
- Fast conversational agents
Supported agent capabilities: Optimal, Speed.
GPT-5.6 Sol
OpenAI's GPT-5.6 flagship model for complex professional work.
Recommended for:
- High complexity use cases
Supported agent capabilities: Optimal, Accuracy, Understanding.
GPT-5.6 Terra
Designed for workloads that balance intelligence and cost.
Recommended for:
- Premium customer experiences
Supported agent capabilities: Optimal, Accuracy, Understanding.
GPT-5.6 Luna
Designed for cost-sensitive, high-volume workloads.
Recommended for:
- Fast conversational agents
Supported agent capabilities: Optimal, Speed.
Claude Opus 5.5
Anthropic describes it as the first model in its Claude 5.5 family.
Recommended for:
- High complexity use cases
Trade-off: Slower. Enterprise plans only.
Supported agent capabilities: Optimal, Accuracy, Understanding.
Claude Opus 5
Anthropic describes it as a thoughtful and proactive model.
Recommended for:
- High complexity use cases
Trade-off: Slower. Enterprise plans only.
Supported agent capabilities: Optimal, Accuracy, Understanding.
Claude Sonnet 5
Anthropic describes it as "built to be the most agentic Sonnet model yet."
Recommended for:
- Premium customer experiences
Trade-off: Enterprise plans only.
Supported agent capabilities: Optimal, Accuracy, Understanding.
Claude Sonnet 5 Reasoning
The reasoning version of Claude Sonnet 5.
Recommended for:
- When multi-step thinking is required
Trade-off: Slower. Enterprise plans only.
Supported agent capabilities: Optimal, Accuracy, Understanding.
Gemini 3 Pro
Google AI's advanced model delivering balanced performance with natural, conversational responses.
Key advantage: Alternative provider option with performance similar to Claude Sonnet 4.5. Offers provider diversity for Enterprise deployments.
Recommended for:
- Advanced customer engagement
- Nuanced, context-aware conversations
- High-quality content generation
- Sophisticated reasoning tasks
Trade-off: Latency
Supported agent capabilities: Optimal, Accuracy, Understanding
Gemini 3 Pro is still in the preview mode on Google's platform. Performance and latency may occasionally be inconsistent.
Gemini 3.1
Google AI's advanced model delivering balanced performance with natural, conversational responses.
Key advantage: Alternative provider option with performance similar to Claude Sonnet 4.5. Offers provider diversity for Enterprise deployments.
Recommended for:
- Advanced customer engagement
- Nuanced, context-aware conversations
- High-quality content generation
- Sophisticated reasoning tasks
Trade-off: Latency
Supported agent capabilities: Optimal, Accuracy, Understanding
Gemini 3.5 Flash
Google AI's lightweight model optimized for faster responses.
Recommended for:
- High-volume query handling
- Quick responses where speed matters
- Straightforward information retrieval
Trade-off: Same performance trade-offs compared to other lightweight models (GPT-4o mini, GPT-4.1 mini, Claude 4.5 Haiku). Best suited for use cases where provider diversity is important. Enterprise plans only.
Supported agent capabilities: Speed, Optimal.
Updated 10 days ago