LLM Inference
Paid OpenAI-compatible chat completions API at https://inference.surf.cascade.fyi. Costs $0.001-$0.003 USDC per call via x402 on Solana. Use the x_payment tool for all requests.
Endpoint
Chat Completions
Generate a chat completion from a supported model.
x_payment({
"url": "https://inference.surf.cascade.fyi/v1/chat/completions",
"method": "POST",
"body": "{\"model\": \"moonshotai/kimi-k2.5\", \"messages\": [{\"role\": \"user\", \"content\": \"Explain x402 in one sentence\"}]}"
})Body Parameters:
| Param | Type | Required | Description |
|---|---|---|---|
| model | string | yes | Model ID (see table below) |
| messages | array | yes | Array of {role, content} objects |
| max_tokens | integer | no | Maximum tokens to generate |
| temperature | number | no | Sampling temperature (0-2) |
| top_p | number | no | Nucleus sampling (0-1) |
Message roles: system, user, assistant
Models & Pricing
| Model | Cost/call | Best for |
|---|---|---|
moonshotai/kimi-k2.5 | $0.003 | High-quality output, large context (262K) |
minimax/minimax-m2.5 | $0.002 | Balanced quality/cost |
Usage Patterns
Simple question
x_payment({
"url": "https://inference.surf.cascade.fyi/v1/chat/completions",
"method": "POST",
"body": "{\"model\": \"moonshotai/kimi-k2.5\", \"messages\": [{\"role\": \"user\", \"content\": \"What is the x402 protocol?\"}]}"
})With system prompt and parameters
x_payment({
"url": "https://inference.surf.cascade.fyi/v1/chat/completions",
"method": "POST",
"body": "{\"model\": \"moonshotai/kimi-k2.5\", \"messages\": [{\"role\": \"system\", \"content\": \"You are a concise technical writer.\"}, {\"role\": \"user\", \"content\": \"Write a summary of Solana's transaction model\"}], \"max_tokens\": 500, \"temperature\": 0.7}"
})Response Format
Standard OpenAI chat completion response:
{
"id": "gen-...",
"object": "chat.completion",
"model": "moonshotai/kimi-k2.5",
"choices": [{
"index": 0,
"message": { "role": "assistant", "content": "..." },
"finish_reason": "stop"
}],
"usage": {
"prompt_tokens": 12,
"completion_tokens": 42,
"total_tokens": 54
}
}Errors
| HTTP | Meaning |
|---|---|
| 400 | Invalid request (check model name and messages format) |
| 402 | Payment required (handled automatically by x_payment) |
| 502 | Upstream provider error |
Cost
Flat rate per model per call. Price is determined by the model field in the request body. Each call is independent - no sessions or state.