Muse Spark vs Muse Spark 1.3
| Benchmark | Muse Spark | Muse Spark 1.3 |
|---|---|---|
| Humanity's Last Exam | 40.7 | 47.5 |
| Terminal-Bench 4.0 | — | 16.7 |
| AutomationBench-AA | — | 56.8 |
| Arena Text · creative writing | 1,465 | 1,461 · max |
| MMMU-Pro (vision) | 80.5 | 82 |
Specs
| Spec | Muse Spark | Muse Spark 1.3 |
|---|---|---|
| Input, per 1M | $1.25 | $1.25 |
| Output, per 1M | $4.25 | $4.25 |
| Cost per task? | — | $1.37 |
| Speed, tok/s | — | 273 |
| Context | 1M | 1M |
| Weights | Closed | Closed |
| Released | Apr 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 n=1 · Meta / Chat Completions›
Requests with n greater than 1 return HTTP 400; request one completion at a time.
Chat Completions cannot carry reasoning · Meta / Chat Completions›
For external keys, Chat Completions redacts reasoning_content to empty and cannot carry reasoning across turns; use Responses when continuity matters.