# Atlas with OpenAI o1 in 2026 > OpenAI o1, the December 2024 model, provides a 200K token context window, making it historically significant for reasoning tasks. OpenAI o1, the original chain-of-thought reasoning model, is useful within Atlas in 2026 primarily as a fixed historical baseline for comparing reasoning progress. While it offers a 200K token context window and is competent at math and logic-heavy debugging, its pricing at $15 per Mtok input and $60 per Mtok output makes it 7.5x more expensive than newer, stronger alternatives like o3 for general agent tasks. ## Key takeaways - OpenAI o1 offers a 200K token context window and 100K max output tokens. - Its pricing is $15 per Mtok input and $60 per Mtok output, making it 7.5x more expensive than o3. - OpenAI o1 is historically important as the original chain-of-thought reasoning model from December 2024. - It remains competent for math and logic-heavy debugging tasks within Atlas. - Weak tool calling compared to GPT-5 class models significantly impacts agent loop efficiency. - Best used in 2026 as a fixed historical baseline for comparing reasoning progress. ## What is OpenAI o1 best at within Atlas? In 2026, OpenAI o1 serves a specific niche within Atlas, primarily as a historical baseline. This model, released in December 2024, was the original chain-of-thought reasoning model and remains competent for tasks requiring significant math and logic-heavy debugging. OpenAI o1, launched in December 2024, holds historical importance as the model that initiated the reasoning line. Within Atlas, it excels at math and logic-heavy debugging, leveraging its foundational chain-of-thought reasoning capabilities. It also offers a substantial 100K maximum output token capacity, matching other models in the o-series. For developers in 2026, OpenAI o1 is particularly useful as a fixed historical baseline, allowing for direct comparison of reasoning progress against newer models like o3 and the GPT-5 line, providing valuable insights into model evolution. ## What are the cost and context tradeoffs for OpenAI o1? OpenAI o1 presents significant cost tradeoffs in 2026, priced at $15 per Mtok for input and $60 per Mtok for output. This makes it 7.5x more expensive than the newer o3 model, despite offering a substantial 200K token context window. The primary tradeoffs for OpenAI o1 in 2026 revolve around its pricing and tool calling capabilities. At $15 per Mtok for input and $60 per Mtok for output, it is considerably more expensive, specifically 7.5x the price of o3, which is a newer and stronger model. While OpenAI o1 does provide a generous 200K token context window and a 100K max output, its cost-effectiveness for routine agent tasks is low. Furthermore, its tool calling capabilities are weak compared to GPT-5 class models, which is a critical factor for efficient operation within an agent loop like Atlas. Developers must weigh the large context window against the higher operational costs and reduced tool interaction efficiency. ## When should I choose a different model over OpenAI o1 for Atlas? In 2026, developers should generally choose a different model over OpenAI o1 for most Atlas agent tasks due to its significant cost and weaker tool calling. Newer models, such as o3, offer 7.5x better pricing and enhanced capabilities for agent loops. You should choose a different model over OpenAI o1 for Atlas in most scenarios in 2026. The model's pricing, at $15 per Mtok input and $60 per Mtok output, makes it 7.5x more expensive than o3, which also offers superior capabilities. Its weak tool calling, especially when compared to GPT-5 class models, significantly hinders its performance in an agent loop where frequent and precise tool interactions are crucial. For general development, code generation, and complex agent workflows, newer models like o3 are far more cost-effective and capable. OpenAI o1 is best reserved for specific historical comparisons or niche debugging tasks where its original reasoning strengths are paramount and cost is not the primary concern. ## How can I optimize Atlas when using OpenAI o1? To optimize Atlas with OpenAI o1 in 2026, developers should leverage Atlas's plan agent to pre-select files, given o1's tendency for fewer, chunkier tool calls. Keeping permissions on 'ask' is also crucial to review shell commands from this older model before they execute. When integrating OpenAI o1 with Atlas, specific optimizations can help mitigate its tradeoffs. Due to o1's tendency to make fewer, chunkier tool calls, it is advisable to lean on Atlas's plan agent to pre-select files. This proactive approach can guide the model more effectively, compensating for its less granular tool interaction. Additionally, given that o1 is an older model, it is crucial to keep Atlas's permissions on 'ask'. This setting ensures that any shell commands proposed by the model are reviewed and approved by the developer before they run, providing an essential safety net against unexpected or inefficient actions. These steps help manage the model's limitations within the Atlas agent framework. ## Setup 1. Set your OpenAI API key as an environment variable: `export OPENAI_API_KEY="sk-..."` 2. Run `atlas models openai` to confirm that `o1` resolves correctly as an available model. 3. Pin `"model": "openai/o1"` in your Atlas configuration. Note that this is primarily recommended for historical comparison, as o3 is 7.5x cheaper and newer. 4. Expect fewer, chunkier tool calls from OpenAI o1; lean on Atlas's plan agent to pre-select files to guide its actions. 5. Keep Atlas's permissions on `ask` so that any shell commands proposed by this older model are reviewed before they run. ## FAQ ### What is the context window for OpenAI o1 in Atlas? OpenAI o1 provides a 200K token context window and supports a 100K token maximum output within Atlas. ### How much does OpenAI o1 cost to use with Atlas? Using OpenAI o1 with Atlas costs $15 per Mtok for input tokens and $60 per Mtok for output tokens. ### Is OpenAI o1 good for general coding tasks in Atlas in 2026? In 2026, OpenAI o1 is generally not recommended for most general coding tasks in Atlas due to its high cost and weaker tool calling compared to newer models like o3. ### Why is OpenAI o1 still listed as an option for Atlas? OpenAI o1 is listed as an option in Atlas primarily for its historical significance as the original chain-of-thought reasoning model and as a fixed baseline for comparing reasoning progress. ### Does OpenAI o1 support tool calling in Atlas? OpenAI o1 does support tool calling in Atlas, but its capabilities are weaker compared to GPT-5 class models, which can impact the efficiency of agent loops. ### How does OpenAI o1 compare to o3 in terms of price and capability? OpenAI o1 is 7.5x more expensive than o3, with o3 being newer and stronger in overall capability, especially for tool calling in agent workflows. ### What are the recommended settings for using OpenAI o1 with Atlas? When using OpenAI o1 with Atlas, it is recommended to lean on Atlas's plan agent to pre-select files and keep permissions on 'ask' to review shell commands before execution. --- Canonical HTML: https://seashell.sh/resources/models/o1 Source of truth: aeo_pages row `/resources/models/o1` (segment: Models) (this file is generated from it, never hand-edited). Licence: SeaShell is proprietary with a free core. It is not open source and there is no public source repository.