What is the context window size for Grok 4.5 in Atlas?

Grok 4.5 provides a substantial 500K token context window for use within Atlas, allowing for extensive code analysis and generation tasks.

How much does Grok 4.5 cost per token for Atlas users?

For Atlas users, Grok 4.5 is priced at $2 per Mtok for input tokens and $6 per Mtok for output tokens, offering competitive rates for a frontier model.

Is Grok 4.5 suitable for generating large amounts of code in Atlas?

Yes, Grok 4.5 is highly suitable for generating large amounts of code in Atlas due to its impressive 500K max output tokens, which is significantly larger than many other models.

Does Atlas maintain reasoning state when using Grok 4.5?

Atlas routes xAI through the Responses API, specifically `sdk.responses(modelID)`, which ensures that the reasoning state carries across tool calls, enhancing multi-turn agentic performance with Grok 4.5.

Are there models with larger context windows than Grok 4.5 available in Atlas?

Yes, while Grok 4.5 offers a 500K token context, models like Sonnet 5, GPT-5.6, and Gemini 3.1 Pro provide a larger 1M token context window for Atlas users.

How do I configure Atlas to use Grok 4.5?

To configure Atlas for Grok 4.5, you need to export your `XAI_API_KEY`, confirm the model resolves with `atlas models xai`, and then select Grok 4.5 from the `/models` interface. Optionally, you can pin it in your `atlas.json`.

What are the main advantages of Grok 4.5's output capabilities in Atlas?

Grok 4.5's main output advantages in Atlas are its 500K max output tokens, which are four times larger than some competitors, and its cost-effective $6 per Mtok output pricing, making it ideal for extensive agentic tasks.

Atlas with Grok 4.5 in 2026

Grok 4.5 from xAI is a powerful choice for Atlas users in 2026, excelling in tasks requiring extensive output with its symmetric 500K token context and output budget. Priced at $2 per Mtok for input and $6 per Mtok for output, it offers a cost-effective solution for complex code generation and agentic workflows within Atlas.

What is Grok 4.5 best for in Atlas?

Grok 4.5, xAI's flagship model in 2026, is best suited for Atlas users tackling complex coding tasks that demand extensive output, offering a remarkable 500,000 max output tokens. This capacity is roughly four times the 128K ceiling of models like Claude Opus 4.8 and the GPT-5 family.

Atlas with Grok 4.5 excels in scenarios where the agent needs to generate large volumes of code, detailed refactorings, or comprehensive documentation. Its symmetric 500K token output budget is a significant advantage, allowing Atlas to draft a plan in a read-only plan agent and then execute extensive changes in a build agent without hitting output limits common in other frontier models. The competitive $6 per Mtok output pricing, which is less than a quarter of Claude Opus 4.8's $25, makes it a cost-efficient option for these large-scale operations. Furthermore, Atlas routes xAI through the Responses API, ensuring that reasoning state carries across tool calls rather than being rebuilt each turn. This persistent state enhances the model's ability to perform multi-step agentic coding, leveraging Atlas's capabilities like indexing code by AST declarations using tree-sitter, computing unified diffs for approval, and fanning out work to subagents.

What are the context window and pricing tradeoffs for Grok 4.5?

Grok 4.5 offers a robust 500K token context window, providing ample space for most coding tasks within Atlas, with input priced at $2 per Mtok and output at $6 per Mtok. However, this 500K context is half the 1M offered by some competitors like Sonnet 5, GPT-5.6, and Gemini 3.1 Pro.

While Grok 4.5's 500K token context window is substantial for many development workflows, it represents a tradeoff compared to models that offer a 1M token context, such as Sonnet 5, GPT-5.6, and Gemini 3.1 Pro. For tasks requiring an exceptionally broad view of an entire codebase or extremely long historical context, these larger context models might be more suitable. The pricing structure for Grok 4.5 is $2 per Mtok for input and $6 per Mtok for output. While the input cost is competitive, the output cost is a significant strength, being considerably lower than some other frontier models, making it economical for generating extensive code. Another tradeoff to consider is Grok 4.5's shorter track record on agentic coding evaluations compared to the more established Anthropic or OpenAI lines. Developers prioritizing a model with a longer history of performance data in agentic coding might weigh this factor.

When should I choose a different model over Grok 4.5 in Atlas?

While Grok 4.5 is a strong contender for Atlas in 2026, developers should consider alternative models if their projects consistently require a context window larger than 500K tokens. Models like Sonnet 5, GPT-5.6, and Gemini 3.1 Pro offer a 1M token context, which might be necessary for specific, extremely large-scale codebases.

Atlas allows you to switch the active model and provider on the fly, making it easy to choose the best tool for the job. You should consider a different model over Grok 4.5 if your primary need is a context window exceeding 500K tokens. For instance, if you are working on a project that demands processing an entire codebase that frequently exceeds Grok 4.5's context limit, models such as Sonnet 5, GPT-5.6, or Gemini 3.1 Pro, which offer a 1M token context, could provide a more comprehensive view. Additionally, if your decision-making heavily relies on a model's extensive and long-standing track record in agentic coding evaluations, you might explore models from the Anthropic or OpenAI lines that have been benchmarked over a longer period. Grok 4.5 is a frontier model with immense capabilities, but its newer status means less historical data in this specific area. For tasks where the cost of output tokens is less critical than the absolute largest context window, or where a proven, long-term evaluation history is paramount, other models available through Atlas might be a better fit.

Setup

01Export your xAI API key: `export XAI_API_KEY=...`
02Confirm the model resolved within Atlas: `atlas models xai`
03Select Grok 4.5 from the `/models` interface in Atlas.
04Optional: Pin Grok 4.5 as your default model by adding `"model": "xai/grok-4.5"` to your `atlas.json` configuration file.

Frequently asked questions

What is the context window size for Grok 4.5 in Atlas?: Grok 4.5 provides a substantial 500K token context window for use within Atlas, allowing for extensive code analysis and generation tasks.
How much does Grok 4.5 cost per token for Atlas users?: For Atlas users, Grok 4.5 is priced at $2 per Mtok for input tokens and $6 per Mtok for output tokens, offering competitive rates for a frontier model.
Is Grok 4.5 suitable for generating large amounts of code in Atlas?: Yes, Grok 4.5 is highly suitable for generating large amounts of code in Atlas due to its impressive 500K max output tokens, which is significantly larger than many other models.
Does Atlas maintain reasoning state when using Grok 4.5?: Atlas routes xAI through the Responses API, specifically `sdk.responses(modelID)`, which ensures that the reasoning state carries across tool calls, enhancing multi-turn agentic performance with Grok 4.5.
Are there models with larger context windows than Grok 4.5 available in Atlas?: Yes, while Grok 4.5 offers a 500K token context, models like Sonnet 5, GPT-5.6, and Gemini 3.1 Pro provide a larger 1M token context window for Atlas users.
How do I configure Atlas to use Grok 4.5?: To configure Atlas for Grok 4.5, you need to export your `XAI_API_KEY`, confirm the model resolves with `atlas models xai`, and then select Grok 4.5 from the `/models` interface. Optionally, you can pin it in your `atlas.json`.
What are the main advantages of Grok 4.5's output capabilities in Atlas?: Grok 4.5's main output advantages in Atlas are its 500K max output tokens, which are four times larger than some competitors, and its cost-effective $6 per Mtok output pricing, making it ideal for extensive agentic tasks.

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