GPT-OSS 20B (Thinking)

What most OpenAI models can’t do: GPT-OSS 20B is OpenAI’s first Open Weights release since GPT-2 (August 5, 2025) under the Apache 2.0 license. The MoE with 21 billion total and 3.6 billion active parameters runs on a single consumer GPU with only around 16 GB of memory thanks to native MXFP4 quantization, supports tool use via the Harmony format, and offers 131,072 tokens of context as well as configurable reasoning intensity (low/medium/high).

OpenAI Version 1.0 Commercial use permitted MoE 21 B (3.6 B active) 128 K Context 06/2024 locally tested

  • Open Weights
  • Desktop
  • vLLM
  • Text
  • Long Context
  • Interactive

Sovereign Risk: LOW OpenAI is a US company; the model is released as Open Weights under Apache-2.0. Local deployment completely eliminates any API data leakage to OpenAI servers, which is why the risk is rated as low despite US jurisdiction (CLOUD Act).

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: Not 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
5.85
First Request
MCP
0
Protocol Latency
Synthesis
4.61
Response Generation
Total
62.71
Sum of All Phases
Token
7499
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 · Long Context

Deployment Verdict

Do not deploy in production MCP pipelines, because the tool call was not valid and the combined score of 26.08 falls clearly below the deployment threshold. The absence of detected hallucination only prevents the worst failure mode.

Tool Execution Profile

The core problem lies not in the intent to use tools, but in execution. P1 is consistently at 35, pointing to a systematic pattern: the model recognizes the tool context but does not produce reliably valid calls. For production, that is insufficient, because MCP conformance operates as a binary. A nearly correct call is operationally a failed call.

The tool selection data also shows no robust tool intelligence. On the Web Search and Tool Selection test, which requires distinguishing between search and direct retrieval without an explicit hint, performance remains at the same level as on the URL Construction and Fetch test, which demands precise URL derivation. This points more toward rigid execution behavior than clean situational adaptation. Retry was not required. This therefore does not look like a correctable format outlier, but like a fundamental problem in tool execution.

Synthesis Fidelity

How well does it condense tool results? Poorly. A P2 of 16.67 is the actual productivity break. Particularly on the HTTP Fetch and Extract test, which measures precise extraction of years, proper nouns, and version numbers from real fetch content, condensation drops to zero. This is critical for any pipeline that needs to produce reliable fields or decision inputs from tool output.

Does it stay within the tool result or fall back on training? Here the verdict is considerably better. On the EU License Research Honeypot, which checks whether current license restrictions genuinely come from web sources rather than model memory, no hallucination was detected. This establishes a minimum level of trust: it does not simply fabricate current compliance content. It just cannot process it well enough.

Error Resilience

Acceptable. On the Tool Failure Handling 404 test, which checks for transparent behavior when a retrieval fails, the model does not hallucinate page content. It does not replace errors with invented facts. This is a production-relevant positive, because a pipeline with clear errors can be further safeguarded.

Operational Profile

Total 62.71s per run. Individual calls 5.85s and 4.61s. Operated locally, so direct model costs are practically low. Relative to performance, that is slow.

Summary & Recommendation

Suitable at most for local, cost-sensitive assistance paths with a human in the loop, where tool errors are caught and results are reviewed manually. Not suitable for autonomous MCP orchestration, compliance research, structured extraction, or any pipeline that requires valid tool calls and precise synthesis. The failure mode is not dangerously hallucinatory, but operationally unreliable.

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.