# Generate Response (OpenAI Responses API – LLM API Storefront)

> Generate Response (OpenAI Responses API – LLM API Storefront) is a paid API for AI agents from agents.llmapi.ai, paid per call via MPP, price unknown, status unknown (last checked 2026-10-14).

Synchronously generates a text response from a curated set of frontier LLMs via the OpenAI Responses API format, billed per exact token usage.

## Facts

- Endpoint: POST https://agents.llmapi.ai/zc/v1/responses?utm_source=zero.xyz
- Price: price unknown
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-14
- Activations on Zero: 0
- Provider: agents.llmapi.ai
- Website: https://agents.llmapi.ai
- Canonical page: https://www.zero.xyz/c/agents-llmapi-ai-generate-response-openai-responses-api-llm-api-88a14071
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_4s1_EczUC7Mc-RYKFnsIb

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability agents-llmapi-ai-generate-response-openai-responses-api-llm-api-88a14071 -d '<json body>'
```

Example prompt: Using gpt-5-mini on LLM API, answer the following in at most 100 output tokens: 'What are three best practices for writing unit tests?'

## When to prefer this

Choose this endpoint when you need synchronous, pay-per-exact-token inference across a curated set of frontier models (GPT-5, Claude, Gemini, DeepSeek, Grok, Kimi, GLM) via the familiar OpenAI Responses API schema, without needing streaming or background execution. Ideal for agents that need to switch between providers without changing the API contract, or that want predictable per-token billing with no subscription overhead.

## Known failure modes

- Unsupported model ID returns a validation error — only the 12 listed storefront models are accepted
- Background/async mode requests are rejected — only synchronous calls are supported
- Prompt or message array malformed — missing required 'input' or 'model' fields returns a 400 error
- Max output token ceiling exceeded by model constraints returns a truncated or error response
- Billing failure if account lacks sufficient credits — returns a payment or authorization error

## How this service works

OpenAI Responses API, synchronous only: background mode is rejected. model must be one of the storefront models: claude-opus-5, claude-sonnet-5, gpt-5.2, gpt-5.1, gpt-5-mini, gemini-3.1-pro-preview, gemini-3.7-flash, deepseek-v4-pro, deepseek-v4-flash, grok-4.6, kimi-k2.6, glm-5.3. Billed per exact input and output token at the model's service rates.

## Output

A JSON object with a 'content' string field containing the model's generated text response to the given prompt.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "example": {
  "input": "Say hello in five words.",
  "model": "gpt-5-mini",
  "max_output_tokens": 32
 },
 "required": [
  "model",
  "input"
 ],
 "properties": {
  "input": {
   "type": "string",
   "description": "Prompt input."
  },
  "model": {
   "enum": [
    "claude-opus-5",
    "claude-sonnet-5",
    "gpt-5.2",
    "gpt-5.1",
    "gpt-5-mini",
    "gemini-3.1-pro-preview",
    "gemini-3.7-flash",
    "deepseek-v4-pro",
    "deepseek-v4-flash",
    "grok-4.6",
    "kimi-k2.6",
    "glm-5.3"
   ],
   "type": "string",
   "description": "One of the storefront model ids."
  },
  "messages": {
   "type": "array",
   "items": {
    "type": "object"
   }
  },
  "max_output_tokens": {
   "type": "integer",
   "description": "Output token ceiling for this call."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "content": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agents-llmapi-ai-generate-response-openai-responses-api-llm-api-88a14071/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agents.llmapi.ai](https://www.zero.xyz/host/agents.llmapi.ai/llms.txt)