fetch_trace
Retrieve detailed trace data by ID from Langfuse to debug LLM applications, with options for observation inclusion and output formats.
Instructions
Get a single trace by ID with full details.
Args:
ctx: Context object containing lifespan context with Langfuse client
trace_id: The ID of the trace to fetch (unique identifier string)
include_observations: If True, fetch and include the full observation objects instead of just IDs.
Use this when you need access to system prompts, model parameters, or other details stored
within observations. Significantly increases response time but provides complete data.
output_mode: Controls the output format and detail level
Returns:
One of the following based on output_mode:
- For 'compact' and 'full_json_file': A response dictionary with the structure:
{
"data": Single trace object,
"metadata": {
"file_path": Path to saved file (only for full_json_file mode),
"file_info": File save details (only for full_json_file mode)
}
}
- For 'full_json_string': A string containing the full JSON response
Usage Tips:
- For quick browsing: use include_observations=False with output_mode="compact"
- For full data but viewable in responses: use include_observations=True with output_mode="compact"
- For complete data dumps: use include_observations=True with output_mode="full_json_file"Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| trace_id | Yes | The ID of the trace to fetch (unique identifier string) | |
| include_observations | No | If True, fetch and include the full observation objects instead of just IDs. Use this when you need access to system prompts, model parameters, or other details stored within observations. Significantly increases response time but provides complete data. Pairs well with output_mode='full_json_file' for complete dumps. | |
| output_mode | No | Controls the output format and action. 'compact' (default): Returns a summarized JSON object optimized for direct agent consumption. 'full_json_string': Returns the complete, raw JSON data serialized as a string. 'full_json_file': Returns a summarized JSON object AND saves the complete data to a file. | compact |
Output Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |