# Meta Model API vs Muse Spark Open

> Muse Spark Open scores 53.4 (D) to Meta Model's 52.2 (D) for llm inference. Prices, MCP, x402, uptime and agent notes side by side.

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- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
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- Updated: 2026-10-15

Muse Spark Open scores 53.4 (D) on agent readiness against Meta Model API's 52.2 (D), and leads in 5 of 7 scored categories. Meta Model API leads on agent ergonomics and security & auth. Both do llm inference.

- Meta Model API: grade D, 52.2/100, rank #794 of 1095. Markdown https://www.anchorterminal.com/tools/meta-model-api.md · JSON https://www.anchorterminal.com/api/v1/tools/meta-model-api.json
- Muse Spark Open: grade D, 53.4/100, rank #760 of 1095. Markdown https://www.anchorterminal.com/tools/muse-spark-open.md · JSON https://www.anchorterminal.com/api/v1/tools/muse-spark-open.json
- Best model APIs and inference for AI agents: https://www.anchorterminal.com/best/inference/index.md
- All 210 models comparisons: https://www.anchorterminal.com/compare/inference/index.md

## Which one, for what

### Meta Model API (D)

Good for: Long-running agent and coding work over text, images, video, audio and PDFs with a 1M-token context, where training must stay off by default.

Ahead on:
- Agent ergonomics, 75 against 69
- Security & auth, 64 against 44

Also in its favour:
- A hosted endpoint, with nothing to install

Watch for: Muse Wonder is labelled a preview, and no deprecation policy or notice period was found

### Muse Spark Open (D)

Good for: A team with a four-GPU Blackwell node, or two to four Mac Studios, that wants a 1M-token multimodal coding and agent model on its own hardware with no prompts leaving it.

Ahead on:
- Payments & pricing, 50 against 20
- Maintenance & community, 60 against 46

Also in its favour:
- No key needed to call it

Watch for: The NVFP4 checkpoint (about 537 GB) serves on four B300 GPUs and the BF16 one (about 1.65 TB) on eight


## Score by category

| Category | Weight | Meta Model API | Muse Spark Open | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 40 | 42 | Muse Spark Open +2 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 60 | 61 | Muse Spark Open +1 |
| Agent ergonomics | 13% (16.2 this run) | 75 | 69 | Meta Model API +6 |
| Security & auth | 14% (17.5 this run) | 64 | 44 | Meta Model API +20 |
| Payments & pricing | 10% (12.5 this run) | 20 | 50 | Muse Spark Open +30 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 46 | 60 | Muse Spark Open +14 |
| Transparency & trust | 7% (8.8 this run) | 52 | 53 | Muse Spark Open +1 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **52.2 · D** | **53.4 · D** | |

## Facts side by side

| Fact | Meta Model API | Muse Spark Open |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Meta | Meta |
| Hosted endpoint | `https://api.meta.ai/v1` | no (local only) |
| Transports | HTTP | HTTP |
| Auth | API key | None |
| Pricing | Pay per use | Free |
| x402 | no | no |
| Licence | Closed service under the Meta Model API Terms of Service (last updated 9 October 2026), with Meta Platforms, Inc., or Meta Platforms Ireland Limited in the European Region, as the contracting party. | Muse Model Licence (source-available weights, not an OSI licence), free of charge with an attribution notice, a separate agreement with Meta before Model as a Service by a licensee group above $20M gross revenue, and the Muse Spark Open Usage Policy |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-10-12 | 2026-10-15 |
| Terms last updated |  |  |
| Privacy policy last updated | couldn't be read | no document linked |
| Customer content may train models |  |  |
| Terms restrict automated access |  |  |
| Terms restrict benchmarking |  |  |
| Terms or service can change without notice |  |  |
| Arbitration or class-action waiver |  |  |

## Verdicts

**Meta Model API.** Meta Model API serves Muse Wonder, in preview since 12 October 2026, and Muse Spark with 1M-token context, constrained JSON Schema output, automatic prompt caching and per-token prices published without a login. Standard-mode content is not used for training. There's no free allowance, status history, OpenAPI file, deprecation policy or way to force a tool call.

**Muse Spark Open.** Muse Spark Open runs on the owner's hardware in seven runtimes, with OpenAI-compatible servers in vLLM and SGLang, standard tool calls, a 1M-token context and Meta's own serving docs. Serving the 537 GB NVFP4 checkpoint takes four B300 GPUs, Meta's download is gated by manual review, and the licence adds attribution and a revenue threshold for model resellers.

## Before you call either

### Meta Model API

1. Use `muse-wonder-1.0` for long multi-step work and `muse-spark-1.3` for cheaper, high-volume calls. Both take the same requests
2. Keep personal or confidential data away from `-contributor` model IDs. Meta may train on that content
3. Honour Retry-After on 429 and 503, which is 60 seconds for `service_overloaded`, and check `GET https://api.meta.ai/v1/status`, which needs no key
4. Pass the key to the OpenAI SDK explicitly or set `OPENAI_API_KEY`. The SDK doesn't read `MODEL_API_KEY`
5. Leave `tool_choice` at `auto`. The docs say `none` and `required` are not supported

### Muse Spark Open

1. Start vLLM or SGLang with `--reasoning-parser muse --tool-call-parser muse` (vLLM also `--enable-auto-tool-choice`), or tool calls come back as raw text
2. Set `reasoning_effort` to `low` or `medium` for short tasks. The default is `xhigh`, reasoning can't be turned off, and other values return an error
3. Stop only on `<|eot|>` and end of text. Stopping on `<|eom|>` cuts off tool calls and final answers
4. Stream long generations and leave `max_tokens` room for reasoning, or `content` can come back empty with `finish_reason` `length`
5. Don't call Meta Model API for this model. Use a self-hosted server or a hosted provider's model string, such as `meta-models/muse-spark-open`

## Questions

### Which is better for AI agents, Meta Model API or Muse Spark Open?

Muse Spark Open scores 53.4 (D) on agent readiness against Meta Model API's 52.2 (D), and leads in 5 of 7 scored categories. Meta Model API leads on agent ergonomics and security & auth.

### Do Meta Model API and Muse Spark Open need an API key?

Meta Model API needs an API key. Muse Spark Open needs no key.

### Can an agent call Meta Model API and Muse Spark Open without installing anything?

Meta Model API has a hosted endpoint at https://api.meta.ai/v1. No hosted endpoint is listed for Muse Spark Open.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/meta-model-api-vs-muse-spark-open.json, and with the fewest tokens: https://www.anchorterminal.com/compare/meta-model-api-vs-muse-spark-open.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "meta-model-api", "b": "muse-spark-open"}`. From a terminal: `anchor compare meta-model-api muse-spark-open`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/meta-model-api.json and https://www.anchorterminal.com/api/v1/tools/muse-spark-open.json

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