AI Gateway REST: xai/grok-4.5 native web_search broken (search_parameters 500s; /responses rejects Responses shape)

[elijahbowie]

Summary

Native web search for xai/grok-4.5 is broken / unsupported on the documented Cloudflare AI REST path (POST /client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/v1/...), despite the grok-4.5 model page advertising search_parameters, web_search_options, and tools on chat completions.

Basic chat completions for xai/grok-4.5 succeed (HTTP 200). Any attempt to enable native search fails in one of two contradictory ways depending on endpoint/shape.

Root-cause framing

This looks like a docs / gateway wiring gap, not an upstream xAI outage:

1. The AI Gateway web search docs explicitly state that only xai/grok-4.20-multi-agent-0309 accepts web_search via AI Gateway, on POST /ai/v1/responses with input + tools: [{ "type": "web_search" }].
2. The same docs list other Grok chat-completions models under “Models without web search support,” but do not mention xai/grok-4.5.
3. The xai/grok-4.5 model page exposes search_parameters, web_search_options, and tools on the chat-completions schema — implying search is available — but those fields fail in practice.
4. Sending a Responses-API-shaped body (input + tools: [{type:"web_search"}]) to /ai/v1/responses for xai/grok-4.5 is rejected as if the gateway is treating the request as chat completions (unsupported field input; expects messages).

Hypothesis: AI Gateway only wires native xAI web_search for the multi-agent model on the Responses path. xai/grok-4.5 is catalogued with search-related schema fields, but the gateway does not implement chat-side search_parameters / web_search_options, nor Responses-side web_search for this model ID.

Environment

• Product: FRAME (Workers / Agents SDK app)
• Client: @ai-sdk/openai chat completions against Cloudflare OpenAI-compatible AI REST
• Base URL: https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/v1
• Auth: Authorization: Bearer $CLOUDFLARE_API_TOKEN (Unified Billing / account token; no per-vendor xAI key)
• Model: xai/grok-4.5
• Date observed: 2026-07-22

Steps to reproduce

1. Baseline — chat without search (works)

curl -sS -X POST "https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/v1/chat/completions" \
  --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \
  --header "Content-Type: application/json" \
  --data '{
    "model": "xai/grok-4.5",
    "messages": [
      { "role": "user", "content": "Say hello in one sentence." }
    ]
  }'

Actual: HTTP 200 with a normal chat completion.

2. Chat completions with search_parameters (fails — HTTP 500)

curl -sS -X POST "https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/v1/chat/completions" \
  --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \
  --header "Content-Type: application/json" \
  --data '{
    "model": "xai/grok-4.5",
    "messages": [
      { "role": "user", "content": "What were the top news stories about Cloudflare this week? Summarize in three bullets." }
    ],
    "search_parameters": {
      "mode": "auto",
      "return_citations": true
    }
  }'

Also fails with the equivalent top-level web_search_options body (same endpoint / model).

Actual:

HTTP 500
{
  "errors": [
    {
      "message": "Model execution failed (Error)",
      "code": 2002
    }
  ],
  "success": false
}

3. Responses-shaped request on /ai/v1/responses (fails — HTTP 400)

This is the shape documented for xAI web search on the multi-agent model, adapted to xai/grok-4.5:

curl -sS -X POST "https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/v1/responses" \
  --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \
  --header "Content-Type: application/json" \
  --data '{
    "model": "xai/grok-4.5",
    "input": "What were the top news stories about Cloudflare this week? Summarize in three bullets.",
    "tools": [
      { "type": "web_search" }
    ]
  }'

Actual: HTTP 400 rejecting field input and indicating the gateway expects messages (chat-completions shape), not Responses API input.

Expected

Either:

A (preferred): Native web search works for xai/grok-4.5 on the documented AI REST path — ideally both:

• Chat completions: search_parameters / web_search_options (as advertised on the model page), and/or
• Responses: input + tools: [{ "type": "web_search" }] (as documented for xAI in the web search guide)

…and ideally also xAI-native x_search / code_execution tools where applicable.

B: If intentionally unsupported, the grok-4.5 model page should not advertise search_parameters / web_search_options, and the web search docs should list xai/grok-4.5 under “Models without web search support” (or explicitly document the supported model list only). Failures should be a clear 4xx validation error, not an opaque HTTP 500 code: 2002.

Ask

Please support native web_search (and ideally x_search / code_execution) for xai/grok-4.5 on the documented AI REST / AI Gateway path, or clarify the model-page params if they are intentionally unsupported.

If the intended path is only xai/grok-4.20-multi-agent-0309 on /ai/v1/responses, please:

1. Wire xai/grok-4.5 the same way (or document why it cannot be), and
2. Align the model-page schema + “Models without web search support” list so developers are not sent down a 500 path.

Related docs

• https://developers.cloudflare.com/ai-gateway/usage/web-search/
• https://developers.cloudflare.com/ai/models/xai/grok-4.5/

Notes

• No existing cloudflare/ai issue appears to cover grok-4.5 + web_search / search_parameters specifically (searched 2026-07-22).
• Related but distinct: AI Gateway REST: /ai/v1/responses rejects Unified Billing on an authenticated gateway #548 (Unified Billing rejection on /ai/v1/responses), AI Gateway doesn't supports Azure OpenAPI Responses API #399 (Azure Responses API support). This report is specifically about xAI Grok 4.5 native search capability and endpoint/schema mismatch.