Is Mercury 2 available on FastMetal?

Not at the moment. Mercury 2.5, from the same lab, is available on the FastMetal API today.

What is the context window of Mercury 2?

128,000 tokens, shared between the prompt and the response.

How does Mercury 2 rank?

#209 on the public arena's Overall board (ELO 1,347). Ranks move as the leaderboard is updated.

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inception/mercury-2

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Mercury 2

Mercury 2 is an extremely fast reasoning LLM, and the first reasoning diffusion LLM (dLLM). Instead of generating tokens sequentially, Mercury 2 produces and refines multiple tokens in parallel, achieving >1,000 tokens/sec on standard GPUs. Mercury 2 is 5x+ faster than leading speed-optimized LLMs like Claude 4.5 Haiku and GPT 5 Mini, at a fraction of the cost. Mercury 2 supports tunable reasoning levels, 128K context, native tool use, and schema-aligned JSON output. Built for coding workflows where latency compounds, real-time voice/search, and agent loops. OpenAI API compatible. Read more in the [blog post](https://www.inceptionlabs.ai/blog/introducing-mercury-2).

3/4/2026

128,000 tokens

#124 Code (Overall)

Specifications

Modalities

Input

text

Output

text

Supported Parameters

include_reasoning

max_tokens

reasoning

response_format

stop

structured_outputs

temperature

tool_choice

tools

Max Output Tokens

50,000

Reasoning Configuration

Default: Thinking on (effort: medium)
Selectable effort levels: high
medium
low
none
Turning thinking off: Possible (reasoning.enabled: false)

How to control thinking, and what it costs

Frequently asked questions

Is Mercury 2 available on FastMetal?: Not at the moment. Mercury 2.5, from the same lab, is available on the FastMetal API today.
What is the context window of Mercury 2?: 128,000 tokens, shared between the prompt and the response.
How does Mercury 2 rank?: #209 on the public arena's Overall board (ELO 1,347). Ranks move as the leaderboard is updated.