How to records first_token_time for your runs?

[uznadeem]

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Example Code

curl -X POST "https://api.smith.langchain.com/api/v1/runs" \
-H "Content-Type: application/json" \
-H "x-api-key: <API KEY HERE>" \
-d '{
  "name": "uzair3",
  "run_type": "llm",
  "start_time": "2025-01-24T16:05:30Z",
  "end_time": "2025-01-24T16:05:34Z",
  "first_token_time": "2025-01-24T16:05:34Z",
  "inputs": { 
    "system_message": "Your role is to answer questions accurately.",
    "user_message": "What is the capital of France?"
  },
  "outputs": {
    "response": "The capital of France is Paris."
  }
}'

Description

• We want to track Time to First Token for our runs.

• From the documentations I see we need to use first_token_time for that.

• I had tried passing "first_token_time": "2025-01-24T16:05:34Z", with my request in multiple formats but it is recording it as "first_token_time":null

Here is my output:

curl -X GET "https://api.smith.langchain.com/api/v1/runs/9a2c2694-1ae5-4949-8968-f2a41cb0f602" \
-H "Content-Type: application/json" \
-H "x-api-key: <API KEY HERE>" \


{"name":"uzair3","inputs":{"system_message":"Your role is to answer questions accurately.","user_message":"What is the capital of France?"},"inputs_preview":"Your role is to answer questions accurately.","run_type":"llm","start_time":"2025-01-24T16:05:30","end_time":"2025-01-24T16:05:34","extra":null,"error":null,"execution_order":1,"serialized":null,"outputs":{"response":"The capital of France is Paris."},"outputs_preview":"The capital of France is Paris.","parent_run_id":null,"manifest_id":null,"manifest_s3_id":null,"events":[],"tags":[],"inputs_s3_urls":null,"outputs_s3_urls":null,"s3_urls":null,"trace_id":"9a2c2694-1ae5-4949-8968-f2a41cb0f602","dotted_order":"20250124T160530000000Z9a2c2694-1ae5-4949-8968-f2a41cb0f602","id":"9a2c2694-1ae5-4949-8968-f2a41cb0f602","status":"success","child_run_ids":null,"direct_child_run_ids":null,"parent_run_ids":[],"feedback_stats":null,"reference_example_id":null,"total_tokens":0,"prompt_tokens":0,"completion_tokens":0,"total_cost":null,"prompt_cost":null,"completion_cost":null,"price_model_id":null,"first_token_time":null,"session_id":"6de1a1bb-654a-44d7-8eb2-48f13833ac2d","app_path":"/o/1754faa3-0e76-408a-8517-996d9ab3fffb/projects/p/6de1a1bb-654a-44d7-8eb2-48f13833ac2d/r/9a2c2694-1ae5-4949-8968-f2a41cb0f602?trace_id=9a2c2694-1ae5-4949-8968-f2a41cb0f602&start_time=2025-01-24T16:05:30","last_queued_at":null,"in_dataset":false,"share_token":null,"trace_tier":"shortlived","trace_first_received_at":"2025-01-24T16:25:10.989689","ttl_seconds":1209600,"trace_upgrade":false,"reference_dataset_id":null}

System Info

CURL request