[BUG] Zen Go Anthropic endpoint: tools requests fail for all GLM models ([1210] / 422 'web_search' translation error) #42616

Description

On the OpenCode Zen Go Anthropic-compatible endpoint (https://opencode.ai/zen/go/v1/messages), any request with a non-empty tools array fails for all GLM models (glm-5.3, glm-5.2, glm-5.1). The same request without tools, or with the same tools against other models (kimi-k3, qwen3.7-plus), succeeds — so this looks like a broken Anthropic→GLM tools translation in the Console Go gateway, not a client or account issue.

This effectively makes GLM models unusable from Claude Code, which always sends tools.

Environment

• Endpoint: POST https://opencode.ai/zen/go/v1/messages (Anthropic-compatible, Go plan)
• Client: plain curl (reproduces without any client), and Claude Code
• Reproduced with 3 independent Go plan API keys (3 separate workspaces) — identical errors, so account-independent
• Date: 2026-08-15

Repro 1 — glm-5.3 + one minimal tool → [1210]

curl -X POST https://opencode.ai/zen/go/v1/messages \
  -H "x-api-key: <REDACTED>" \
  -H "anthropic-version: 2023-06-01" -H "content-type: application/json" \
  -d '{
    "model": "glm-5.3",
    "max_tokens": 2048,
    "tools": [{
      "name": "get_weather",
      "description": "query weather",
      "input_schema": {
        "type": "object",
        "properties": {"city": {"type": "string"}},
        "required": ["city"]
      }
    }],
    "messages": [{"role": "user", "content": [{"type": "text", "text": "What is the weather in Beijing? Please call the tool."}]}]
  }'

Response:

{"error":{"type":"server_error","message":"Error from provider (Console Go): Upstream request failed: [1210] Invalid API parameter, please check the documentation."}}

Notes:

• "tools": [] (empty array) → 200 OK, so it's specifically non-empty tools.
• Fails regardless of tool shape (with/without description, with extra type field, complex schemas).

Repro 2 — glm-5.2 / glm-5.1 + same tool → 422 with revealing param path

{"error":{"param":"tools.0.function-after[_domain_filters(), WebSearchTool].type","type":"invalid_request_error","message":"Error from provider (Console Go): Upstream request failed: [invalid_request_error] Input should be 'web_search'"}}

The mangled param path tools.0.function-after[_domain_filters(), WebSearchTool].type suggests the gateway is translating ordinary Anthropic function tools into Zhipu's web_search tool format before forwarding upstream.

Control experiments (why I believe it's a gateway translation bug)

So: the GLM models themselves handle tools fine (OpenAI endpoint + Zhipu native Anthropic endpoint both work), the Zen Anthropic endpoint's tool translation works fine for other vendors (kimi/qwen) — the failure is specific to the Anthropic→GLM tools translation path in the Console Go gateway.

Expected behavior

tools on the Anthropic-compatible endpoint should work for GLM models the same way it does for kimi-k3 / qwen3.7-plus on the same endpoint, and for glm-5.3 on the OpenAI endpoint.

Additional notes

• glm-5.3 appears to be newly added to the model list (around 2026-08-14).
• Side observation: on Zhipu's native Anthropic endpoint, requesting glm-5.2 now returns "model": "glm-5.3" in the response — the alias seems to have been repointed upstream. Not sure if that's related to the routing difference between the [1210] (glm-5.3) and 422 (glm-5.2/5.1) errors.