Muse Spark 1.2 レビュー：ベンチマーク、API、価格、コーディングテスト

Muse Spark 1.2 combines unusually low token pricing with a 1M-token context window, and it passed all three base-model coding tasks in our first-attempt API suite. Meta launched the model on August 5, 2026, with a 1 million tokens context window, two API pricing tiers, and a separate terminal agent called Muse Code. Meta’s benchmark results are promising; independent public coding leaderboards have not yet verified the same model-and-agent combinations.

This review separates the model from the agent, official scores from independent evidence, and standard pricing from the Contributor tier’s data-use trade-off. In our tests, the model completed a Python idempotency fix, a compatibility-preserving TypeScript refactor, and a repository-wide JSONL feature with no retries. Muse Code agent execution was not tested, and tool-call reliability was not tested. If you are comparing the wider field first, our guide to the コーディングに最適なAIモデル gives the broader competitive context.

Muse Spark 1.2 Review: Quick Answer

The short version: Muse Spark 1.2 is a coding-focused Meta model with a 1M-token window, OpenAI SDK-compatible API access, and an attention-grabbing Contributor tier. Its strongest public story is value: $0.10 input and $0.20 output per million tokens on the Contributor model. That tier may be used to improve Meta products, while the more expensive standard model is not used for that purpose.

The performance story needs more restraint. Meta reports 82.9% on Terminal-Bench 2.1 for Muse Spark 1.2 with Muse Code and 59.3% on DeepSWE. Those are Meta-run results. The public Terminal-Bench and DeepSWE boards did not list Muse Spark 1.2 when checked on August 7, 2026. Artificial Analysis offers a useful independent cross-check, where the current Intelligence Index is 57 and the model ranks #12 of 185.

• Best reason to try it now: low Contributor pricing, large context, and an API that follows the familiar OpenAI client pattern.
• Best reason to stay cautious: three controlled base-model tasks do not establish Muse Code agent reliability, tool-call quality, or performance across a large production repository.
• Important privacy choice: use the standard model for code or prompts you do not want used to improve Meta products.

Muse Spark 1.2 at a Glance

Meta describes Muse Spark 1.2 as a model with higher first-attempt coding accuracy and more reliable tool calling than Muse Spark 1.1. Those are provider claims from the official Muse Spark model page, not conclusions from our own coding session.

Muse Spark 1.2 vs Muse Code

Muse Spark 1.2 is the model. Muse Code is a separate beta terminal agent powered by that model. This distinction matters because an agent can add planning, tool orchestration, repository navigation, worktree isolation, logging, and retry behavior around the underlying model.

について official Muse Code page calls the product a beta coding agent. That makes comparisons with products such as Claude Code and Codex more useful than pretending every observed workflow difference comes from a bare model call. Our Codex と Claude のコード比較 explains why the surrounding agent can change the developer experience as much as the model.

Muse Spark 1.2 Benchmarks: What the Scores Really Show

Meta’s benchmark chart puts Muse Spark 1.2 near the top of several coding evaluations. The numbers are worth examining, but they are not a single clean ranking of raw model quality. The model, agent, harness, reasoning strength, and task protocol can all change together.

Meta-reported Terminal-Bench 2.1

The 82.9% figure is a Meta-run Muse Code result. . public Terminal-Bench 2.1 leaderboard did not list Muse Spark 1.2 on August 7, 2026, so it is not a verified public leaderboard entry. The public board did list Muse Spark 1.1 with mini-SWE-agent at 76.2% ±1.2%.

Meta-reported DeepSWE 1.1

について public DeepSWE v1.1 leaderboard uses mini-swe-agent across its listed models for consistency. It had not added Muse Spark 1.2 when checked; Muse Spark 1.1 was listed at 53%. Meta’s 59.3% result uses Muse Code, so the two numbers are not harness-identical.

Meta’s internal and general-agent evaluations

Meta’s evaluation methodology says Terminal-Bench uses all 89 tasks and pass@1 over five attempts. DeepSWE covers 113 tasks across 91 repositories and five languages, also with pass@1 over five attempts. Meta also notes that its setup may not be optimally tuned for third-party models. For a current competitor comparison built around real product decisions, see Claude Opus 5 対 GPT-5.6.

Artificial Analysis: useful independent context

現在の Artificial Analysis model page gives Muse Spark 1.2 an Intelligence Index of 57, ranking it #12 of 185. Its harness reports 80% on Terminal-Bench v2.1, 57% normalized on GDPVal-AA v2, 56% on SciCode, and 83% on the AA-LCR long-context evaluation.

The practical lesson is simple: Muse Spark 1.2 looks competitive, but no single score isolates the model. Treat Meta’s chart as evidence for the Muse Code system, public leaderboards as a separate cross-check, and Artificial Analysis as an independent but differently configured evaluation.

Muse Spark 1.2 Pricing and Privacy Trade-offs

Meta offers two API model IDs with dramatically different prices. The cheaper option is not merely a discount: it changes how submitted data may be used.

Contributor pricing is 12.5× cheaper for input, 75× cheaper for cached input, and 21.25× cheaper for output than the standard tier. There is no honest single discount percentage that describes every token type.

A Meta researcher promoted the Contributor tier as “up to 250× cheaper” than Fable and “150× cheaper” than GPT-5.6 Sol. That social comparison uses the Contributor prices, not the standard model, and should always carry the data-use qualification. Readers comparing current competitor costs can use our separate GPT-5.6 価格ガイド そして Claude Code pricing breakdown.

For public repositories, synthetic tasks, or disposable evaluation fixtures, the Contributor tier may be appealing. For private code, customer data, credentials, or proprietary architecture, the standard tier is the safer default. Meta also says it is beginning to accept zero-data-retention requests through sales, which is a separate access path rather than the default self-serve setting.

Muse Spark 1.2 API Access and Example

について Meta Model API supports an OpenAI SDK-compatible workflow. Meta’s official cookbook uses the base URL https://api.meta.ai/v1 and reads the key from MODEL_API_KEY. The product page also describes search grounding, while the cookbook covers chat completions, streaming, tool calling, structured output, prompt caching, reasoning controls, vision, long context, retries, and search recipes.

Official cookbook example — captured version: について official GitHub cookbook still uses muse-spark-1.1. This proves the client structure and base URL, not that the example has been refreshed for 1.2.

import os

from openai import OpenAI

client = OpenAI(
    base_url="https://api.meta.ai/v1",
    api_key=os.environ["MODEL_API_KEY"],
)

response = client.chat.completions.create(
    model="muse-spark-1.1",
    messages=[{"role": "user", "content": "Hello, world!"}],
)

print(response.choices[0].message.content)

Documented adaptation — not executed: Meta separately lists muse-spark-1.2 as the standard 1.2 model ID. The minimal substitution below combines two official facts, but no paid request was sent during this review.

response = client.chat.completions.create(
    model="muse-spark-1.2",
    messages=[{"role": "user", "content": "Hello, world!"}],
)

Muse Spark is a reasoning model, and reasoning tokens are billed as output. That makes the $4.25 standard output rate more important than it first appears: an apparently short answer can still carry material hidden reasoning usage. Real latency, time to first token, retry rate, and per-task cost remain unmeasured here.

What Muse Code Adds

Muse Code is installed from the terminal and wraps Muse Spark 1.2 in an agent workflow. Meta’s developer deep dive describes several behaviors that do not belong to a bare API call:

• Parallel agents: tasks can run in isolated git worktrees.
• Append-only event log: sessions and actions are written to local JSONL for audit and replay.
• Resume flow: muse resume can continue interrupted sessions.
• Reasoning control: the /努力 command adjusts reasoning strength.
• Explicit skills: Meta names /taste, /grilling, /grill-with-docs, そして /plan.

That feature set makes Muse Code relevant to the broader coding-agent market, where planning, isolation, replay, and tool discipline matter alongside model intelligence. The OpenClaw vs Claude Code vs OpenCode guide is useful context for those product-level differences.

Launch Claims and Early Community Signals

AI at Meta says Muse Spark 1.2 received more coding-training compute, more varied environments, greater emphasis on whole-repository generation and debugging, and co-training with Muse Code. A separate launch thread describes a stress test lasting up to 24 hours with more than 1,000 tool calls on NVIDIA Hopper GPUs.

That is an impressive demonstration, but it is not a measured general success rate. It does not tell us how often the agent chose the right tool, recovered from errors, avoided duplicate calls, or finished a normal repository task without steering.

Early Reddit posts are similarly mixed. One r/opencode user reported a positive OpenCode experience and praised the price. A separate Contributor-pricing discussion raised data-use, standard-tier cost, availability, and reliability questions. These are individual reactions, not community consensus.

Muse Spark 1.2 Coding Tests: 3/3 Tasks Passed

In our tests, the base Muse Spark 1.2 model completed three controlled coding tasks through an OpenAI-compatible chat-completions API. Each task received one attempt, with zero retries and no human steering. We evaluated the returned files in disposable repositories against public and hidden checks. Muse Code agent execution was not tested, and tool-call reliability was not tested, so these results should not be read as an agent benchmark.

Test 1: Python idempotency bug fix — Pass

The original hidden evaluator incorrectly required a duplicate call to return False, even though the task only required that it not charge the sender twice. After correcting that invented return-value requirement, the unchanged first response passed all six tests. We did not retry or edit the model output.

Test 2: TypeScript multi-file refactor — Pass

The first evaluator compared objects with raw JSON.stringify, so equivalent objects with different key insertion order looked unequal; its Windows npx launch also failed before type-checking. With an order-insensitive comparator and a Windows-safe command invocation, the original response passed every check. Again, there was no model retry.

Test 3: JSONL repository feature — Pass

What the tests show: Muse Spark 1.2 can return usable multi-file patches, respect compatibility constraints, add tests, and handle a modest repository-wide feature in one attempt. The average reported cost was about $0.0151 per task, but these fixtures were small and should not be used to forecast a large codebase bill.

Who Should Use Muse Spark 1.2?

Try it now

Muse Spark 1.2 is worth a controlled evaluation if you work with public or synthetic code, need a 1M-token context window, already use the OpenAI client pattern, and can verify returned patches locally. Its 3/3 result here strengthens the case for a trial, while the Contributor tier remains especially compelling for disposable benchmarks where its data-use terms are acceptable.

Wait for more evidence

Wait if your decision depends on Muse Code agent behavior, stable rate limits, repeated tool-call accuracy, or broad independent repository benchmarks. Three small first-attempt passes answer more than a launch chart, but they do not establish production reliability.

Use the standard tier or compare alternatives

Use the standard model for sensitive code unless your organization has separately approved the Contributor terms. If the standard output price changes the value calculation, compare it with current Codex pricing, Claude Code, and other coding-agent costs before committing to a workflow.

Muse Spark 1.2 Review Verdict

Muse Spark 1.2 earns a place on the evaluation shortlist, not an automatic production recommendation. The 1M-token context, familiar API shape, low Contributor pricing, three first-attempt coding passes, and strong Meta-run Muse Code scores make it hard to ignore. Meta has also done a better job than many launches at publishing methodology details.

The caveats are equally concrete. Contributor pricing comes with a data-use trade-off. Standard output and reasoning tokens can raise the real cost. Meta’s top coding numbers have not been reproduced as matching entries on the public Terminal-Bench or DeepSWE boards, and our hands-on sample covers three base-model tasks rather than Muse Code agent execution.

The sensible move is a controlled trial on non-sensitive code with raw usage and local verification saved. Treat the measured cost and latency as a small-task sample, then test your own repository size, failure recovery, and agent workflow before choosing it for production.

Muse Spark 1.2 FAQ