Composer 2.5 vs Grok 4 Heavy
Composer 2.5 (2026) and Grok 4 Heavy (2025) compare an IDE-native agent built on Kimi K2.5 against a standalone API model. Composer 2.5 ships a 1m-token context window, while Grok 4 Heavy ships a 256k-token context window. This page treats the result as workflow and deployment fit, not a universal model winner.
Use Composer 2.5 when you want the packaged IDE-native agent built on Kimi K2.5 workflow; use Grok 4 Heavy when you need a model you can route, wrap, or run outside that product surface.
Decision scorecard
Local evidence first| Signal | Composer 2.5 | Grok 4 Heavy |
|---|---|---|
| Product type | IDE-native agent built on Kimi K2.5 | Standalone API model |
| Best for | Long Cursor IDE sessions and autonomous in-IDE coding | API builders, multimodal apps, and non-IDE automation |
| Decision fit | Coding, RAG, and Agents | Coding, Long context, and Vision |
| Context window | 1m | 256k |
| Cheapest output | $2.50/1M tokens | - |
| Provider routes | 1 tracked | 0 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- Composer 2.5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Composer 2.5 has broader tracked provider coverage for fallback and procurement flexibility.
- Composer 2.5 uniquely exposes Function calling, Tool use, and Code execution in local model data.
- Local decision data tags Composer 2.5 for Coding, RAG, and Agents.
- Grok 4 Heavy uniquely exposes Vision and Multimodal in local model data.
- Local decision data tags Grok 4 Heavy for Coding, Long context, and Vision.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Composer 2.5
$1,025
Cheapest tracked route/tier: Cursor Standard async
Grok 4 Heavy
Unavailable
No complete token price in local provider data
Cost delta unavailable until both models have sourced input and output token prices.
Switch friction
- No overlapping tracked provider route is sourced for Composer 2.5 and Grok 4 Heavy; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Function calling, Tool use, and Code execution before moving production traffic.
- Grok 4 Heavy adds Vision and Multimodal in local capability data.
- No overlapping tracked provider route is sourced for Grok 4 Heavy and Composer 2.5; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Vision and Multimodal before moving production traffic.
- Composer 2.5 adds Function calling, Tool use, and Code execution in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-05-18 | 2025-07-09 |
| Context window | 1m | 256k |
| Parameters | — | — |
| Architecture | - | - |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Not released | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | - | 2024-11 |
Pricing and availability
| Pricing attribute | Composer 2.5 | Grok 4 Heavy |
|---|---|---|
| Input price |
| - |
| Output price |
| - |
| Providers | - |
Capabilities
| Capability | Composer 2.5 | Grok 4 Heavy |
|---|---|---|
| Vision | No | Yes |
| Multimodal | No | Yes |
| Reasoning | No | No |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | No | No |
| Code execution | Yes | No |
| IDE integration | Yes | No |
| Computer use | No | No |
| Parallel agents | Yes | No |
Benchmarks
No shared benchmark scores are currently available for this pair.
Deep dive
The capability footprint differs most on vision: Grok 4 Heavy, multimodal input: Grok 4 Heavy, function calling: Composer 2.5, tool use: Composer 2.5, and code execution: Composer 2.5. Both models share the core language-model surface, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
Pricing coverage is uneven: Composer 2.5 has $0.50/1M input tokens and Grok 4 Heavy has no token price sourced yet. Provider availability is 1 tracked routes versus 0. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Composer 2.5 when coding workflow support, larger context windows, and broader provider choice are central to the workload. Choose Grok 4 Heavy when vision-heavy evaluation are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which has a larger context window, Composer 2.5 or Grok 4 Heavy?
Composer 2.5 supports 1m tokens, while Grok 4 Heavy supports 256k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Is Composer 2.5 or Grok 4 Heavy open source?
Composer 2.5 is listed under Proprietary. Grok 4 Heavy is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Composer 2.5 or Grok 4 Heavy?
Grok 4 Heavy has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Composer 2.5 or Grok 4 Heavy?
Grok 4 Heavy has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for function calling, Composer 2.5 or Grok 4 Heavy?
Composer 2.5 has the clearer documented function calling signal in this comparison. If function calling is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Composer 2.5 and Grok 4 Heavy?
Composer 2.5 is available on Cursor. Grok 4 Heavy is available on the tracked providers still being sourced. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-06-30. Data sourced from public model cards and provider documentation.