Muse Spark 1.2 vs Muse Spark 1.3
| Benchmark | Muse Spark 1.2 | Muse Spark 1.3 |
|---|---|---|
| Arena Text · creative writing | 1,445 | 1,461 · max |
| EQ-Bench Longform Creative Writing 1.11 | 81.5 | 82.8 |
| EQ-Bench Creative Writing v3 | 1,840.4 | 1,905.9 |
| Lech Mazur Short-Story | -0 · high | 0.6 · high |
| Harvey LAB-AA 1.1 | — | 8.9 · max |
Specs
| Spec | Muse Spark 1.2 | Muse Spark 1.3 |
|---|---|---|
| Input, per 1M | $1.25 | $1.25 |
| Output, per 1M | $4.25 | $4.25 |
| Cost per task? | $0.97 | $1.37 |
| Speed, tok/s | 355 | 273 |
| Context | 1M | 1M |
| Weights | Closed | Closed |
| Released | Aug 2026 | Sep 2026 |
| See images | ✓ | ✓ |
| Read PDFs | ✓ | ✓ |
| Hear audio | — | — |
| Watch video | ✓ | ✓ |
| Call tools | ✓ | ✓ |
| Force a tool call | — | — |
| Return strict JSON | ✓ | ✓ |
| Search the web | ✓ | ✓ |
| Run code | ? | ? |
| Use a computer | ? | ? |
What breaks when you switch
Only auto tool_choice is supported›
tool_choice none, required or a named function returns HTTP 400; use auto and handle either a tool call or text.
Search filters return HTTP 400 · Messages API›
allowed_domains, blocked_domains and max_uses return HTTP 400 on Messages search grounding; omit them and use the supported web_search tool.
Manual budget does not set effort · Messages API›
Compatibility budget_tokens does not set reasoning effort; use output_config.effort for depth control.
No Chat Completions search grounding · Chat Completions›
Search grounding is unavailable in Chat Completions; use Responses or Messages.
Reasoning cannot be disabled›
Muse Wonder and Muse Spark do not support disabling reasoning with none; keep reasoning enabled.
Private reasoning still costs tokens›
Private reasoning consumes the output budget and billed output tokens; budget for it even though it is absent from the response body.
Only auto tool_choice is supported›
tool_choice none, required or a named function returns HTTP 400; use auto and handle either a tool call or text.
Reasoning cannot be disabled›
Muse Wonder and Muse Spark do not support disabling reasoning with none; keep reasoning enabled.