Can't use high reasoning effort with anthropic/claude-opus-4-5

Bug Reports
1

:bug: Describe the Bug

When calling “anthropic/claude-opus-4-5" model via agentic research API with “high” reasoning effort the API returns 400 “invalid request” error. It works without issues with reasoning effort set to “low” and “medium”.

:white_check_mark: Expected Behavior

API request completed successfully.

:cross_mark: Actual Behavior

API returned 400 “invalid request” error.

:counterclockwise_arrows_button: Steps to Reproduce

$ export PERPLEXITY_API_KEY="...key value..."
$ curl https://api.perplexity.ai/v1/responses \
  -H "Authorization: Bearer $PERPLEXITY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "anthropic/claude-opus-4-5",
    "input": "calculate 2+2=",
    "reasoning": {
      "effort": "high"
    }
  }'

:pushpin: API Request & Response (if applicable)

Request:

{
    "model": "anthropic/claude-opus-4-5",
    "input": "calculate 2+2=",
    "reasoning": {
        "effort": "high"
    }
}

response:

{"error":{"message":"invalid request","type":"invalid_request","code":400}}

:globe_showing_europe_africa: Environment

  • API Version: Current (no idea how to check)
  • SDK (if applicable): N/A
  • Operating System: Linux

:paperclip: Logs or Screenshots (if applicable)

Trying all three reasoning effort values:

$ curl https://api.perplexity.ai/v1/responses   -H "Authorization: Bearer $PERPLEXITY_API_KEY"   -H "Content-Type: application/json"   -d '{
    "model": "anthropic/claude-opus-4-5",
    "input": "calculate 2+2=",
    "reasoning": {
      "effort": "low"
    }
  }'
{"created_at":1770384358,"id":"resp_9d79fcd9-a36c-4cdf-8747-4ecd3a643c38","model":"anthropic/claude-opus-4-5","object":"response","output":[{"content":[{"text":"2 + 2 = **4**","type":"output_text"}],"id":"msg_11c3891e-87ef-4180-9ca8-978706bc8f1b","role":"assistant","status":"completed","type":"message"}],"status":"completed","usage":{"cost":{"currency":"USD","input_cost":0.0005,"output_cost":0.00145,"total_cost":0.00195},"input_tokens":99,"output_tokens":58,"total_tokens":157}}
$ curl https://api.perplexity.ai/v1/responses   -H "Authorization: Bearer $PERPLEXITY_API_KEY"   -H "Content-Type: application/json"   -d '{
    "model": "anthropic/claude-opus-4-5",
    "input": "calculate 2+2=",
    "reasoning": {
      "effort": "medium"
    }
  }'
{"created_at":1770384371,"id":"resp_43b3499f-f2be-4e52-8ada-1a5a7a73ecea","model":"anthropic/claude-opus-4-5","object":"response","output":[{"content":[{"text":"2 + 2 = **4**","type":"output_text"}],"id":"msg_d43ef1f1-6eee-4937-91ed-80748b52b079","role":"assistant","status":"completed","type":"message"}],"status":"completed","usage":{"cost":{"currency":"USD","input_cost":0.0005,"output_cost":0.00125,"total_cost":0.00175},"input_tokens":99,"output_tokens":50,"total_tokens":149}}
$ curl https://api.perplexity.ai/v1/responses   -H "Authorization: Bearer $PERPLEXITY_API_KEY"   -H "Content-Type: application/json"   -d '{
    "model": "anthropic/claude-opus-4-5",
    "input": "calculate 2+2=",
    "reasoning": {
      "effort": "high"
    }
  }'
{"error":{"message":"invalid request","type":"invalid_request","code":400}}