Grok 4.20 Multi-Agent vs Phi 3.5 MoE Instruct
Grok 4.20 Multi-Agent (2026) and Phi 3.5 MoE Instruct (2024) are frontier reasoning models from xAI and Microsoft Research. Grok 4.20 Multi-Agent ships a 2m-token context window, while Phi 3.5 MoE Instruct ships a 128k-token context window. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads. It focuses on practical selection signals rather than broad model-family marketing.
Grok 4.20 Multi-Agent fits 16x more tokens; pick it for long-context work and Phi 3.5 MoE Instruct for tighter calls.
Decision scorecard
Local evidence first| Signal | Grok 4.20 Multi-Agent | Phi 3.5 MoE Instruct |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | general production evaluation |
| Decision fit | RAG, Agents, and Long context | Long context |
| Context window | 2m | 128k |
| Cheapest output | $2.50/1M tokens | $0.50/1M tokens |
| Provider routes | 3 tracked | 1 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Grok 4.20 Multi-Agent has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Grok 4.20 Multi-Agent has broader tracked provider coverage for fallback and procurement flexibility.
- Grok 4.20 Multi-Agent uniquely exposes Vision, Multimodal, and Reasoning in local model data.
- Local decision data tags Grok 4.20 Multi-Agent for RAG, Agents, and Long context.
- Phi 3.5 MoE Instruct has the lower cheapest tracked output price at $0.50/1M tokens.
- Local decision data tags Phi 3.5 MoE Instruct for Long context.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Grok 4.20 Multi-Agent
$1,625
Cheapest tracked route/tier: xAI Console
Phi 3.5 MoE Instruct
$525
Cheapest tracked route/tier: Fireworks AI
Estimated monthly gap: $1,100. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Grok 4.20 Multi-Agent and Phi 3.5 MoE Instruct; plan for SDK, billing, or endpoint changes.
- Phi 3.5 MoE Instruct is $2/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision, Multimodal, and Reasoning before moving production traffic.
- No overlapping tracked provider route is sourced for Phi 3.5 MoE Instruct and Grok 4.20 Multi-Agent; plan for SDK, billing, or endpoint changes.
- Grok 4.20 Multi-Agent is $2/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Grok 4.20 Multi-Agent adds Vision, Multimodal, and Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-03-10 | 2024-08-20 |
| Context window | 2m | 128k |
| Parameters | — | 16x3.8B (42B, 6.6B active) |
| Architecture | - | decoder only |
| License | Proprietary | MIT(OSI) |
| Openness | Proprietary | Open source |
| Commercial use | Commercial use with conditions | Commercial use allowed |
| Knowledge cutoff | 2024-11 | 2023-10 |
Pricing and availability
| Pricing attribute | Grok 4.20 Multi-Agent | Phi 3.5 MoE Instruct |
|---|---|---|
| Input price |
| $0.50/1M tokens |
| Output price |
| $0.50/1M tokens |
| Providers |
Capabilities
| Capability | Grok 4.20 Multi-Agent | Phi 3.5 MoE Instruct |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | No |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: Grok 4.20 Multi-Agent, multimodal input: Grok 4.20 Multi-Agent, reasoning mode: Grok 4.20 Multi-Agent, function calling: Grok 4.20 Multi-Agent, tool use: Grok 4.20 Multi-Agent, and structured outputs: Grok 4.20 Multi-Agent. 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.
For cost, Grok 4.20 Multi-Agent lists tiered pricing: 0-200,001t is $1.25/1M input and $2.50/1M output; 200,001t+ is $2.50/1M input and $5/1M output, while Phi 3.5 MoE Instruct lists $0.50/1M input and $0.50/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Phi 3.5 MoE Instruct lower by about $1.13 per million blended tokens. For tiered rows, this cheapest-track view can understate interactive or fast-lane spend, so compare the tier you will actually use. Availability is 3 providers versus 1, so concentration risk also matters.
Choose Grok 4.20 Multi-Agent when reasoning depth, larger context windows, and broader provider choice are central to the workload. Choose Phi 3.5 MoE Instruct when provider fit and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Grok 4.20 Multi-Agent or Phi 3.5 MoE Instruct?
Grok 4.20 Multi-Agent supports 2m tokens, while Phi 3.5 MoE Instruct supports 128k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Grok 4.20 Multi-Agent or Phi 3.5 MoE Instruct?
Grok 4.20 Multi-Agent lists tiered pricing: 0-200,001t is $1.25/1M input and $2.50/1M output; 200,001t+ is $2.50/1M input and $5/1M output. Phi 3.5 MoE Instruct lists $0.50/1M input and $0.50/1M output tokens on the cheapest tracked provider. Compare the tier you will actually use; cheap async pricing can overstate savings for interactive workflows. Provider discounts or batch pricing can still change the final bill.
Is Grok 4.20 Multi-Agent or Phi 3.5 MoE Instruct open source?
Grok 4.20 Multi-Agent is listed under Proprietary. Phi 3.5 MoE Instruct is listed under MIT. 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, Grok 4.20 Multi-Agent or Phi 3.5 MoE Instruct?
Grok 4.20 Multi-Agent 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, Grok 4.20 Multi-Agent or Phi 3.5 MoE Instruct?
Grok 4.20 Multi-Agent 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.
Where can I run Grok 4.20 Multi-Agent and Phi 3.5 MoE Instruct?
Grok 4.20 Multi-Agent is available on OpenRouter, xAI Console, and Vercel AI Gateway. Phi 3.5 MoE Instruct is available on Fireworks AI. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-05-22. Data sourced from public model cards and provider documentation.