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OpenAI logoGPT-6.1 Terra Fast

Efficient reasoning with image understanding and clear writing.

gpt-6.1-terra-fast

Best for: Visual reasoning, document analysis and clear writing

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Catalog status

Enabled

Research checked

2026-11-06

Benchmark results

No recorded results

Results are source-attributed, not TokenRex measurements. Different tests and thinking variants are not interchangeable.

Published benchmark coverage

Reviewed sources do not include results for this exact version. Provider specifications and API capabilities remain listed separately.

Model specifications

Context window

1.05M

Published provider limit

Maximum output

128K

Published provider limit

Knowledge cutoff

June 1, 2026

Upstream model

Thinking

Low, Medium, High, Extra high and Max; Max requires Responses. Native none is also accepted.

Documented capability

Responses

Streaming, function tools, strict JSON and built-in web search verified with direct requests.

Documented capability

Input and output modalities

Provider-reported formats; API compatibility is detailed below.

Input

Text
Image

Output

Text
Exact model ID
gpt-6.1-terra-fast
Model type
Chat
Context window
1,050,000 tokens
Maximum output
128,000 tokens
Knowledge cutoff
June 1, 2026
Thinking
Low, Medium, High, Extra high and Max; Max requires Responses. Native none is also accepted.
Responses
Streaming, function tools, strict JSON and built-in web search verified with direct requests.
Fast
Priority serving verified as service_tier fast; 2× standard token rates. Bill the tier actually served.

A context window is the total conversation budget, not a separate maximum input allowance; generated output and reasoning can use that budget. Published provider limits are not independently tested TokenRex request limits.

Standard and Fast versions

Choose from 2 enabled versions. The exact ID determines the version and its price; benchmark scores do not carry over between variants.

GPT-6.1 Terra$0.70 in / $3.50 out per 1M tokens
GPT-6.1 Terra FastSelected$1.40 in / $7.00 out per 1M tokens

Features and tool support

TokenRex’s exposed interface, not every feature advertised by the provider. “Available” describes the implemented interface, not a successful test of every input or tool.

Reasoning configuration

Adjust thinking without changing the model ID: Low, Medium, High, Extra high, Max. Chat Completions uses reasoning_effort; OpenAI Responses uses reasoning.effort. Max requires Responses.

Thinking is a request setting, not a separate model. Per-token rates stay unchanged; actual reasoning usage changes the bill. Fast alone is a separate version.

Provider-specific thinking examples
Request examples
// OpenAI Chat Completions: keep the model ID unchanged
{ "model": "gpt-6-luna", "reasoning_effort": "high", "stream": true,
  "messages": [{ "role": "user", "content": "Review this design." }] }

// OpenAI Responses: Max on an eligible model, same ID
{ "model": "gpt-6-astra", "reasoning": { "effort": "max", "summary": "auto" },
  "stream": true, "store": false, "input": "Review this design." }

// Claude adaptive thinking: POST /v1/messages (Sonnet 5, Opus 5, Opus 5.5
// and Fable 5.1 accept effort up to "max"; Haiku uses a budget instead)
{ "model": "claude-sonnet-5", "thinking": { "type": "adaptive" },
  "output_config": { "effort": "max" }, "max_tokens": 8192, "stream": true,
  "messages": [{ "role": "user", "content": "Review this design." }] }

// Claude Haiku: native token budget, not adaptive thinking
{ "model": "claude-haiku-4-5", "thinking": { "type": "enabled", "budget_tokens": 4000 },
  "max_tokens": 8192, "stream": true,
  "messages": [{ "role": "user", "content": "Review this design." }] }

// Verified Gemini families: Chat Completions reasoning_effort
{ "model": "gemini-3.8-flash", "reasoning_effort": "low", "stream": true,
  "messages": [{ "role": "user", "content": "Review this design." }] }

Coding and agent workflows

Text/code generation and customer-managed tool loops.

Coding benchmark results do not establish a hosted terminal, sandbox, autonomous browser or guaranteed task success.

Streaming answers

Available

Incremental text through TokenRex’s chat endpoint; Claude also has native Messages access.

Customer-defined function tools

Limited

Only customer-defined function tools are forwarded. Model/protocol compatibility applies; your application authorizes and executes every tool.

Forced or named tool selection

Limited

The chat route accepts auto, none and required. A named-tool choice is not forwarded; exact model compatibility is not independently tested.

Images and PDFs

Available

Images and PDFs can be sent in chat messages to every chat model. File size and model limits apply.

Built-in web search

Available

Turn on per request with web_search_options on /v1/chat/completions or a web_search tool on /v1/responses. $7 per 1K searches plus normal tokens; search results add input tokens. Each web search call the model makes is billed, as reported by OpenAI. Terra's upstream search was verified in November 2026; a new search adds its own fee.

Hosted web page fetch

Not exposed

No standalone provider web-fetch tool is exposed; built-in search may read pages as part of a search where the provider does so.

Hosted code execution / computer use

Not exposed

No built-in execution environment or computer-control tool is provided. Code generation is not code execution.

Hosted file search / persistent assistants

Not exposed

No hosted file-search index, Assistants endpoint or persistent provider agent is exposed.

Prompt caching

Available

Reported cache reads and 30-minute/12-hour writes are billed at their separate rates; request 12 hours with prompt_cache_options.ttl on Responses. Above 272,000 input tokens, the entire request uses double input/cache rates and 1.5× output rates. A cache hit is not guaranteed; no cached-output rate exists.

Batch / fine-tuning

Not exposed

No public batch or fine-tuning endpoint is offered here.

Sources and verification

Provider specifications describe the upstream model, not a guarantee of every feature through TokenRex. Prices come from the enabled catalog; benchmark results belong to the exact tested model.

Research notes (7)
  • No separate Fast benchmark results are verified; do not inherit Standard scores.
  • Priority is billed only when the returned tier is fast or priority.
  • Official Standard rates per 1M tokens: $1 input, $5 output, $0.05 cached input, $1.25 cache write (30 minutes); current TokenRex offer applies to these rates.
  • Above 272,000 input tokens, the entire request uses 2× input/cache rates and 1.5× output rates. Fast adds its 2× token multiplier.
  • 12-hour cache writes cost $2.50 per 1M tokens before offer and long-context multipliers; use prompt_cache_options.ttl=12h on Responses. Cached output is not offered.
  • Official launch material mentions benchmark comparisons, but no exact-version numeric scores were verified during this review. Benchmark gaps are left empty; no other model scores are inherited.
  • Maximum-capacity inputs and outputs, repeated cache hits and hosted computer-use execution were not independently tested.