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Agent Toolbox – GPT-OSS-120B Chat Completions
x402
Agent Toolbox – GPT-OSS-120B Chat Completions is a paid API for AI agents from agent-toolbox.zafermemon87.workers.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-29).
OpenAI-compatible chat completion endpoint powered by gpt-oss-120b, an open-weight reasoning model, returning structured responses with visible reasoning traces.
Price / call$0.005
Success—
StatusUnknown
How this service works
OpenAI-compatible chat completion with gpt-oss-120b (OpenAI's open-weight reasoning model): set the base URL to /v1/llm/gpt-oss-120b in any OpenAI SDK. Up to 32,000 characters in and 2,048 tokens out per call, a fixed price per call, no streaming.
Output
Returns an OpenAI-format chat.completion JSON object containing the assistant's reply in choices[0].message.content, an optional reasoning_content field with the model's internal chain-of-thought, token usage breakdown (prompt_tokens, completion_tokens, total_tokens), a finish_reason, and metadata like model name, object type, and a unique completion ID.
Example use cases
Multi-step reasoning for complex questions
“I need you to think through this logic puzzle carefully and show your reasoning: a farmer has 17 sheep, all but 9 die — how many are left, and why? Use the 120B reasoning model and include the chain-of-thought in the response.”
Structured JSON extraction from natural language
“Parse this customer support ticket into a JSON object with fields: 'issue_type', 'urgency', and 'summary'. Ticket: 'My order #4821 never arrived and the tracking page has shown no updates for 6 days.' Use JSON output mode.”
Drafting nuanced long-form content
“Using the gpt-oss-120b model, write a detailed technical explanation (about 400 words) of how transformer attention mechanisms work, aimed at a software engineer who knows Python but has no ML background.”
Technical details
Endpoint
POSThttps://agent-toolbox.zafermemon87.workers.dev/v1/llm/gpt-oss-120b/chat/completions?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a large (120B parameter) open-weight reasoning model with visible chain-of-thought via the OpenAI SDK interface, especially for multi-step inference tasks, structured JSON output, or when you want a drop-in OpenAI-compatible API without OpenAI's proprietary model lock-in. Prefer over smaller models when reasoning quality matters more than latency. Not suitable for streaming use cases or inputs exceeding 32,000 characters.
Side effects
- Input exceeds 32,000 character limit — request rejected
- max_tokens value above 2048 — validation error
- Malformed messages array (missing role or content) — schema error
- Payment failure or insufficient USDC balance — 402 response
- Model unavailable or worker error — 5xx response
- Temperature outside 0–2 range — validation error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| messages | array | OpenAI chat messages: [{role: system|user|assistant, content}] (up to 32,000 characters in total) |
| max_tokens | integer | Default 2048 |
| temperature | number | |
| response_format | object | {"type": "json_object"} for JSON output |
Output
Schema · Response
{
"type": "json",
"example": {
"id": "chatcmpl-2f3cbf59f9204d269ba32770",
"model": "gpt-oss-120b",
"plain": "gpt-oss-120b: The capital of France is Paris.",
"usage": {
"total_tokens": 124,
"prompt_tokens": 78,
"completion_tokens": 46
},
"object": "chat.completion",
"choices": [
{
"index": 0,
"message": {
"role": "assistant",
"content": "The capital of France is Paris.",
"reasoning_content": "User asks: \"In one sentence, what is the capital of France?\" Answer: \"The capital of France is Paris.\" Provide one sentence."
},
"finish_reason": "stop"
}
],
"created": 1792850662
}
}Tags
x402
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