NVIDIA Nemotron 3 Ultra 550B A55B

NVIDIA Nemotron 3 Ultra is NVIDIA’s Frontier reasoning model with 550 billion total and 55 billion active parameters on a hybrid Mamba-Transformer-MoE architecture with LatentMoE routing and MTP layers. The context window spans one million tokens, and reasoning is configurable. Native tool calls and agentic orchestration are supported; available as an Open Weights model under the NVIDIA Open Model License.

NVIDIA Version 3 Ultra Commercial use permitted MoE 550 B (55 B active) 1000 K Context 04/2026 $0.5 / $2.5 per 1M

  • Open Weights
  • Frontier
  • OpenRouter
  • Text
  • Instruction-Tuned
  • Agentic Orchestrator
  • Real-Time

Sovereign Risk: LOW Fully local inference possible without cloud connection. CLOUD Act is only relevant when using the API via NVIDIA infrastructure, not for local deployment of the publicly available weights.

Tool-use profile: 6 assets in detail

Comparison of asset performance (P1/P2/Combined) against the fleet average

Asset performance (radar)

Score Breakdown vs. Fleet Average


Tool-use details

Asset performance, reliability, and runtime profile

CrucibleMark evaluates tool use across 6 independent tests. Click a test name for details.

Reliability

  • Tool Call Valid: No
  • Retry: Not required
  • Hallucination: Detected

Reliability measures how consistently a model actually executes tool calls: Tool Call Valid schema and format accepted, Retry Required successful only after retry, Hallucination Flag fabricated tools or parameters detected. All three green means production-ready.

Runtime profile

Call 1
23.98
First Request
MCP
0.98
Protocol Latency
Synthesis
2.87
Response Generation
Total
167.01
Sum of All Phases
Token
24835
Input + Output
Cost
$0
Cost per Run

The runtime profile shows the latency and cost metrics for the model run: Call 1 First Request, MCP Protocol Latency, Synthesis Response Generation, Total sum of all phases, supplemented by Token input and output and Cost cost per run.

Tool-use review

Created · Instruction-Tuned · Agentic Orchestrator

Deployment Verdict

Conditional deploy, because tool execution is often strong, but synthesis fidelity at Combined 54.75 and invalid tool call behavior are insufficient to sustain an MCP pipeline without tight guardrails.

Tool Execution Profile

The model demonstrates genuine tool intelligence, but not consistently reliable protocol discipline. On the Web Search & Tool Selection test — which checks whether web_search is chosen over fetch without a hint — it decides correctly and achieves full tool execution. That argues against a rigid pattern. On the URL Construction test, which measures derivation of a target URL from the model’s own knowledge, it performs adequately, but not deterministically enough for hard production paths.

The meta-finding is critical: tool_call_valid=False. This does not mean the model fundamentally fails to understand tools. It means the calls or the surrounding format are not consistently MCP-compliant. For an agentic orchestrator in the Frontier class, this is a relevant deficiency. On the positive side, no retry was required. The issue therefore lies more in first-attempt precision than in repeated format failure.

Synthesis Fidelity

How well does it consolidate tool results? Poorly. P2 of 29.17 is the central finding of this run. The model can retrieve information, but loses coherence when condensing, attributing, and cleanly feeding results back into the response. This is most visible in EU License Research and Multilingual Search & Synthesis, where retrieval performance was high but substantive processing dropped to zero. For productive tool pipelines, this is precisely the breaking point: the tool only helps if the model reliably processes its output downstream.

Does it stay within the tool result or fall back on training data? Not reliably enough. On the honeypot EU License Research test — which checks whether current license restrictions are answered from web sources rather than training knowledge — P2 was 0. No hallucination was flagged there, but the global hallucination finding is nonetheless True. This is a security risk. Once a model presents fabricated facts as tool output, the entire infrastructure loses its auditability.

Error Resilience

On the 404 test, which measures transparent handling of a failed tool call against hallucinated replacement content, the model stays on the acceptable side. It does not fabricate page content despite the error. P2 40 is not strong, but operationally workable. What matters for production: it does not obscure the failure.

Operational Profile

Call 1: 23.98s. Call 2: 2.87s. MCP latency: 0.98s. Total: 167.01s. Slow. Cost/run: local. Inference cost is low, but the runtime is unattractive relative to the weak synthesis performance.

Conclusion & Recommendation

Suitable for supervised research pipelines in which a second system validates the response or only raw material is consumed. Not suitable for compliance, policy, licensing, or multilingual knowledge pipelines where tool results must be precisely consolidated and returned without factual drift. If you deploy it, treat it as a tool-proximate collector with strict output validation — not as the final authority on synthesis.

This analysis was generated automatically based on benchmark data. Model used: GPT 4.5 by OpenAI. The raw data and full methodology are documented in the GitHub project.