The short answer: choose by the job, not the headline.
SKY-001 is worth evaluating for CAD and BIM generation; GPT-6 Astra is the documented general-purpose API option for broader reasoning, coding, and document workflows. In Skyfall’s published CAD and BIM comparisons, SKY-001 records lower task time and cost and higher IoU than Astra. Those provider-reported results support a focused engineering evaluation, not a universal model ranking.
For SKY-001 versus GPT-6 Astra, the practical distinction is specialization and access. Skyfall presents an Engineering World Model and an official waitlist. OpenAI documents Astra’s inputs, outputs, tools, API endpoints, and token pricing. Neither a benchmark lead nor an API listing proves that a model can deliver production-ready engineering files for your workflow.
CAD and BIM: the published head-to-head numbers.
The table reproduces Skyfall’s reported results for SKY-001 and GPT-6 Astra, cited in the source list. It separates CAD from BIM because they are different tasks, not interchangeable measurements of engineering ability.
| Task / measure | SKY-001 | GPT-6 Astra |
|---|---|---|
| CAD · Time | 3.9 s | 199 s |
| CAD · Reported task cost | $0.005 | $0.75 |
| CAD · IoU | 79.7% | 79.1% |
| BIM · Time | 1.22 s | 144.6 s |
| BIM · Reported task cost | $0.0024 | $0.446 |
| BIM · IoU | 43.6% | 40.6% |
CAD IoU is 79.7% for SKY-001 versus 79.1% for Astra, a 0.6-percentage-point difference. BIM IoU is 43.6% versus 40.6%, a 3.0-point difference. Skyfall also shows a 42.3% BIM result for Gemini 3.8 Flash; that is not Astra’s score.
IoU, or intersection over union, measures overlap against a reference. It does not by itself establish dimensional accuracy, editable design intent, valid connections, or compliance with engineering requirements. We have not independently reproduced these results or verified enough methodology to judge statistical significance. Calling the CAD scores a tie would be as unsupported as claiming a decisive quality advantage.
Read the benchmark deep-dive for task-time and cost ratios, metric definitions, and the limits of the comparison.
Different purposes mean different workflows.
SKY-001: start with an engineering object.
Skyfall describes a workflow that explores rough 3D designs, decomposes a selected design into parts, builds those parts from 2D sketches, and assembles them. That makes it a relevant candidate when the deliverable is a CAD assembly or BIM model. This is the developer’s description, not a workflow tested by this guide. Our architecture explainer distinguishes those visual plans from executable models.
GPT-6 Astra: start with a general-purpose task.
OpenAI’s documentation, cited in the source list, describes complex reasoning, coding, computer use, research, and document creation. Astra accepts text and images and produces text; documented tools include code interpreter. These capabilities make it relevant to scripts, specifications, and supporting analysis, without establishing native, certified CAD or BIM output.
The boundary matters: generating geometry and writing code that operates a design tool are not the same deliverable. Before comparing models, specify the artifact you need, the software that must open it, and the edits it must survive. A broader assistant and an engineering model may address different stages rather than replace one another.
Benchmark cost is not retail pricing.
Skyfall reports CAD task costs of $0.005 for SKY-001 and $0.75 for Astra, and BIM task costs of $0.0024 and $0.446 respectively. These are costs attached to the published comparison. They are not verified SKY-001 API prices, subscription rates, or a quote for your project.
By contrast, OpenAI lists Astra’s standard API token prices as $10 per million input tokens, $1 per million cached input tokens, and $50 per million output tokens, reviewed October 21, 2026; see the pricing source. Inputs above 272K tokens have different rates. Token prices and benchmark task costs use different units and cannot be directly substituted for one another.
For a purchasing decision, compare cost per accepted deliverable: include retries, tool execution, engineering review, and repair work. A low generation cost can be outweighed by a model that requires substantial manual correction. SKY-001’s commercial pricing remains unverified here; obtain terms from Skyfall before forecasting savings.
Official waitlist versus documented API.
Skyfall’s official waitlist is the confirmed access route in the source reviewed. Our access-request guide explains the steps and links to that official destination. A waitlist does not establish immediate access, eligibility, delivery dates, or a public API contract. It also does not prove that no API or private deployment option exists; ask Skyfall about your requirements.
Astra has published API documentation covering Responses and Chat Completions, linked in the primary sources. That provides a concrete starting point for integration planning, but documentation is not a guarantee of account eligibility, capacity, or suitability for a particular workload. Check current access and service terms before committing an implementation.
For the current evidence checklist, read SKY-001 access, pricing and API status. For the system behind its demonstrations, see how SKY-001 works.
Which model should you evaluate first?
- Your deliverable is editable engineering geometry: investigate SKY-001 first, subject to access. Request representative outputs and inspect parts, constraints, dimensions, and downstream compatibility rather than relying on renders.
- Your deliverable is code, research, or documentation: Astra’s documented scope is the more direct starting point. Test the actual task instead of treating CAD benchmark latency as a proxy for writing or reasoning performance.
- You need an integration plan now: start from Astra’s documented API while confirming account access. For SKY-001, obtain interface, export, deployment, and commercial details directly before designing around assumptions.
- You handle safety-critical or regulated designs: neither cited comparison establishes approval for that use. Keep qualified review and your existing validation process in the acceptance criteria.
Use the same briefs, acceptance rules, and review process for any hands-on comparison you run. Record failures and correction time alongside successful outputs. The winner for your team should be the workflow that produces acceptable results under your constraints, not the largest published speed ratio.
Plan domain-specific checks using the CAD workflow evaluation or BIM handoff evaluation. Editable feature histories and editable building objects are described as next steps in Skyfall’s research article, not established shipping integrations.
Questions before choosing.
Is SKY-001 better than GPT-6 Astra?
Skyfall reports better task time, cost, and IoU for SKY-001 on its CAD and BIM comparisons. That does not establish a better model for unrelated work or guarantee better results on your designs.
Can GPT-6 Astra generate CAD or BIM files?
The cited documentation establishes text output and tools, not certified native CAD or BIM support. Whether a tool-assisted workflow produces valid files needs a separate test in your target application.
Does SKY-001 cost $0.005 per request?
No retail rate is established by that figure. It is Skyfall’s reported CAD benchmark task cost. Public commercial pricing has not been verified by this guide.
Can I try both models through this website?
No. This is an independent information site, not a model provider. Read the SKY-001 access-request steps and the Astra access caveats before visiting the providers’ sites.
Do the IoU scores prove engineering readiness?
No. Overlap is one metric. Production readiness also depends on dimensions, constraints, editability, interoperability, and the checks required by the intended use.
Sources and evidence boundaries.
- Skyfall: SKY-001 official product page — model purpose, described workflow, CAD and BIM comparisons, and waitlist.
- OpenAI: GPT-6 Astra model documentation — documented capabilities, modalities, endpoints, tools, and token pricing.
This comparison separates provider claims from decision criteria. It is not an independent benchmark, endorsement, or purchasing guarantee. For the broader model overview, return to the SKY-001 guide.