When building an agent, you'll choose a model tier that determines the AI brain powering it. Cortex offers three tiers, each balancing speed, cost, and capability differently.

The fast tier is the quickest and most affordable option. It's well suited to straightforward tasks that don't require deep reasoning or complex decision-making- things like formatting data, sending simple notifications, or performing lookups.

Best for: Simple automations, data retrieval, routine notifications.

Trade-off: You lose some reasoning power and nuance compared to higher tiers.

The balanced tier sits in the middle. It offers strong reasoning and language ability at a moderate speed and cost. For most estate agency use cases, this tier will be the right choice.

Best for: Email drafting, applicant qualification, content writing, multi-step workflows.

Trade-off: Slightly slower than fast, slightly less capable than pro.

The pro tier uses the most powerful frontier models available. These models excel at complex reasoning, nuanced copywriting, and tasks that require significant judgement. They are also the slowest and most expensive option.

Best for: Complex decision-making, high-quality long-form content, tasks requiring deep understanding of context.

Trade-off: Higher cost and slower response times.

You'll notice that Cortex doesn't ask you to choose between OpenAI, Anthropic, Google, or any other AI provider. You simply pick a tier, and Cortex handles the rest. There are two reasons for this:

AI providers experience outages and overload regularly. If the primary provider for your chosen tier is unavailable, Cortex will automatically switch to an alternative provider so your agents keep running.

Different AI models have different strengths. Cortex will route your agent's work to the model that's best suited to the specific task at hand, switching behind the scenes as needed. This means you always get the best available performance for your tier without having to understand the differences between providers.

If you're unsure, start with Balanced. It handles the vast majority of tasks well. You can always change the tier later if you find your agent needs more power or if you want to reduce costs on simpler tasks.