--- title: List events for an LLM Observability experiment description: Datadog, the leading service for cloud-scale monitoring. breadcrumbs: Docs > API Reference > LLM Observability --- # List events for an LLM Observability experiment{% #list-events-for-an-llm-observability-experiment %} Copy pageCopied {% tab title="v2" %} **Note**: This endpoint is in preview and is subject to change. If you have any feedback, contact [Datadog support](https://docs.datadoghq.com/help/). | Datadog site | API endpoint | | ----------------- | -------------------------------------------------------------------------------------- | | ap1.datadoghq.com | GET https://api.ap1.datadoghq.com/api/v2/llm-obs/v3/experiments/{experiment_id}/events | | ap2.datadoghq.com | GET https://api.ap2.datadoghq.com/api/v2/llm-obs/v3/experiments/{experiment_id}/events | | app.datadoghq.eu | GET https://api.datadoghq.eu/api/v2/llm-obs/v3/experiments/{experiment_id}/events | | app.ddog-gov.com | GET https://api.ddog-gov.com/api/v2/llm-obs/v3/experiments/{experiment_id}/events | | us2.ddog-gov.com | GET https://api.us2.ddog-gov.com/api/v2/llm-obs/v3/experiments/{experiment_id}/events | | app.datadoghq.com | GET https://api.datadoghq.com/api/v2/llm-obs/v3/experiments/{experiment_id}/events | | us3.datadoghq.com | GET https://api.us3.datadoghq.com/api/v2/llm-obs/v3/experiments/{experiment_id}/events | | us5.datadoghq.com | GET https://api.us5.datadoghq.com/api/v2/llm-obs/v3/experiments/{experiment_id}/events | ### Overview Retrieve spans and experiment-level summary metrics for a given experiment with cursor-based pagination. ### Arguments #### Path Parameters | Name | Type | Description | | ------------------------------- | ------ | ------------------------------------------- | | experiment_id [*required*] | string | The ID of the LLM Observability experiment. | #### Query Strings | Name | Type | Description | | ------------ | ------- | ------------------------------------------------------------------------- | | page[limit] | integer | Maximum number of spans to return per page. Defaults to 5000. | | page[cursor] | string | Opaque cursor from a previous response to fetch the next page of results. | ### Response {% tab title="200" %} OK {% tab title="Model" %} Response for listing experiment events (v2/v3). Returns spans and summary metrics in a single resource. | Parent field | Field | Type | Description | | -------------------- | --------------------------------- | ------------------- | ------------------------------------------------------------------------------------------------------------------ | | | data [*required*] | object | JSON:API data object for an experiment events response. | | data | attributes [*required*] | object | Attributes of an experiment events response. | | attributes | spans [*required*] | [object] | Experiment spans, each enriched with their associated evaluation metrics. | | spans | dataset_record_id | string | ID of the dataset record this span evaluated. | | spans | duration | double | Duration of the span in nanoseconds. | | spans | eval_metrics | [object] | Evaluation metrics associated with this span. | | eval_metrics | assessment | enum | Assessment result for an LLM Observability experiment metric. Allowed enum values: `pass,fail` | | eval_metrics | boolean_value | boolean | Boolean value. Present when `metric_type` is `boolean`. | | eval_metrics | categorical_value | string | Categorical value. Present when `metric_type` is `categorical`. | | eval_metrics | eval_source_type | string | Source type of the evaluation. | | eval_metrics | id | string | Unique identifier of the evaluation metric event. | | eval_metrics | json_value | object | JSON value. Present when `metric_type` is `json`. | | eval_metrics | label | string | Label or name for the metric. | | eval_metrics | metadata | object | Arbitrary metadata associated with the metric. | | eval_metrics | metric_source | string | Source of the metric. Either `custom` (user-submitted) or `summary` (experiment-level aggregate). | | eval_metrics | metric_type | enum | Type of metric recorded for an LLM Observability experiment. Allowed enum values: `score,categorical,boolean,json` | | eval_metrics | reasoning | string | Human-readable reasoning for the metric value. | | eval_metrics | score_value | double | Numeric score. Present when `metric_type` is `score`. | | eval_metrics | span_id | string | Span ID this metric is associated with. | | eval_metrics | tags | [string] | Tags associated with the metric. | | eval_metrics | timestamp_ms | int64 | Timestamp when the metric was recorded, in milliseconds since Unix epoch. | | eval_metrics | trace_id | string | Trace ID linking this metric to a span. | | spans | id | string | Unique identifier of the span. | | spans | meta | object | Metadata associated with an experiment span. | | meta | error | object | Error details for an experiment span. | | error | message | string | Error message. | | error | stack | string | Stack trace of the error. | | error | type | string | The error type or exception class name. | | meta | expected_output | object | Expected output for the span, used for evaluation. | | meta | input | object | Represents any valid JSON value. | | input | Option 1 | string | A scalar string value. | | input | Option 2 | double | A scalar numeric value. | | input | Option 3 | object | An arbitrary object value with additional properties. | | input | Option 4 | [ ] | An array of arbitrary values. | | Option 4 | Option 1 | string | A scalar string value. | | Option 4 | Option 2 | double | A scalar numeric value. | | Option 4 | Option 3 | object | An arbitrary object value with additional properties. | | Option 4 | Option 4 | boolean | A scalar boolean value. | | input | Option 5 | boolean | A scalar boolean value. | | meta | output | object | Represents any valid JSON value. | | output | Option 1 | string | A scalar string value. | | output | Option 2 | double | A scalar numeric value. | | output | Option 3 | object | An arbitrary object value with additional properties. | | output | Option 4 | [ ] | An array of arbitrary values. | | Option 4 | Option 1 | string | A scalar string value. | | Option 4 | Option 2 | double | A scalar numeric value. | | Option 4 | Option 3 | object | An arbitrary object value with additional properties. | | Option 4 | Option 4 | boolean | A scalar boolean value. | | output | Option 5 | boolean | A scalar boolean value. | | spans | metrics | object | Numeric metrics attached to the span. | | additionalProperties | | double | | spans | name | string | Name of the span. | | spans | parent_id | string | Parent span ID, if any. | | spans | span_id | string | Span ID. | | spans | start_ns | int64 | Start time in nanoseconds since Unix epoch. | | spans | status | enum | Status of the span. Allowed enum values: `ok,error` | | spans | tags | [string] | Tags associated with the span. | | spans | trace_id | string | Trace ID. | | attributes | summary_metrics [*required*] | [object] | Experiment-level summary evaluation metrics (not tied to individual spans). | | summary_metrics | assessment | enum | Assessment result for an LLM Observability experiment metric. Allowed enum values: `pass,fail` | | summary_metrics | boolean_value | boolean | Boolean value. Present when `metric_type` is `boolean`. | | summary_metrics | categorical_value | string | Categorical value. Present when `metric_type` is `categorical`. | | summary_metrics | eval_source_type | string | Source type of the evaluation. | | summary_metrics | id | string | Unique identifier of the evaluation metric event. | | summary_metrics | json_value | object | JSON value. Present when `metric_type` is `json`. | | summary_metrics | label | string | Label or name for the metric. | | summary_metrics | metadata | object | Arbitrary metadata associated with the metric. | | summary_metrics | metric_source | string | Source of the metric. Either `custom` (user-submitted) or `summary` (experiment-level aggregate). | | summary_metrics | metric_type | enum | Type of metric recorded for an LLM Observability experiment. Allowed enum values: `score,categorical,boolean,json` | | summary_metrics | reasoning | string | Human-readable reasoning for the metric value. | | summary_metrics | score_value | double | Numeric score. Present when `metric_type` is `score`. | | summary_metrics | span_id | string | Span ID this metric is associated with. | | summary_metrics | tags | [string] | Tags associated with the metric. | | summary_metrics | timestamp_ms | int64 | Timestamp when the metric was recorded, in milliseconds since Unix epoch. | | summary_metrics | trace_id | string | Trace ID linking this metric to a span. | | data | id [*required*] | string | Identifier for this events resource. | | data | type [*required*] | enum | Resource type for an experiment events collection. Allowed enum values: `experiment_events` | | | meta | object | Pagination cursor metadata. | | meta | after | string | Cursor for the next page of results. | {% /tab %} {% tab title="Example" %} ```json { "data": { "attributes": { "spans": [ { "dataset_record_id": "string", "duration": 1500000000, "eval_metrics": [ { "assessment": "pass", "boolean_value": false, "categorical_value": "string", "eval_source_type": "managed", "id": "00000000-0000-0000-0000-000000000001", "json_value": {}, "label": "faithfulness", "metadata": {}, "metric_source": "custom", "metric_type": "score", "reasoning": "string", "score_value": "number", "span_id": "span-7a1b2c3d", "tags": [], "timestamp_ms": 1705314600000, "trace_id": "abc123def456" } ], "id": "00000000-0000-0000-0000-000000000001", "meta": { "error": { "message": "Model response timed out", "stack": "Traceback (most recent call last):\n File \"main.py\", line 10, in \n response = model.generate(input)\n File \"model.py\", line 45, in generate\n raise TimeoutError(\"Model response timed out\")\nTimeoutError: Model response timed out", "type": "TimeoutError" }, "expected_output": {}, "input": { "description": "undefined", "type": "undefined" }, "output": { "description": "undefined", "type": "undefined" } }, "metrics": { "": "number" }, "name": "llm_call", "parent_id": "string", "span_id": "span-7a1b2c3d", "start_ns": 1705314600000000000, "status": "ok", "tags": [], "trace_id": "abc123def456" } ], "summary_metrics": [ { "assessment": "pass", "boolean_value": false, "categorical_value": "string", "eval_source_type": "managed", "id": "00000000-0000-0000-0000-000000000001", "json_value": {}, "label": "faithfulness", "metadata": {}, "metric_source": "custom", "metric_type": "score", "reasoning": "string", "score_value": "number", "span_id": "span-7a1b2c3d", "tags": [], "timestamp_ms": 1705314600000, "trace_id": "abc123def456" } ] }, "id": "3fd6b5e0-8910-4b1c-a7d0-5b84de329012", "type": "experiment_events" }, "meta": { "after": "string" } } ``` {% /tab %} {% /tab %} {% tab title="400" %} Bad Request {% tab title="Model" %} API error response. | Parent field | Field | Type | Description | | ------------ | ------------------------ | -------- | ------------------------------------------------------------------------------- | | | errors [*required*] | [object] | A list of errors. | | errors | detail | string | A human-readable explanation specific to this occurrence of the error. | | errors | meta | object | Non-standard meta-information about the error | | errors | source | object | References to the source of the error. | | source | header | string | A string indicating the name of a single request header which caused the error. | | source | parameter | string | A string indicating which URI query parameter caused the error. | | source | pointer | string | A JSON pointer to the value in the request document that caused the error. | | errors | status | string | Status code of the response. | | errors | title | string | Short human-readable summary of the error. | {% /tab %} {% tab title="Example" %} ```json { "errors": [ { "detail": "Missing required attribute in body", "meta": {}, "source": { "header": "Authorization", "parameter": "limit", "pointer": "/data/attributes/title" }, "status": "400", "title": "Bad Request" } ] } ``` {% /tab %} {% /tab %} {% tab title="401" %} Unauthorized {% tab title="Model" %} API error response. | Parent field | Field | Type | Description | | ------------ | ------------------------ | -------- | ------------------------------------------------------------------------------- | | | errors [*required*] | [object] | A list of errors. | | errors | detail | string | A human-readable explanation specific to this occurrence of the error. | | errors | meta | object | Non-standard meta-information about the error | | errors | source | object | References to the source of the error. | | source | header | string | A string indicating the name of a single request header which caused the error. | | source | parameter | string | A string indicating which URI query parameter caused the error. | | source | pointer | string | A JSON pointer to the value in the request document that caused the error. | | errors | status | string | Status code of the response. | | errors | title | string | Short human-readable summary of the error. | {% /tab %} {% tab title="Example" %} ```json { "errors": [ { "detail": "Missing required attribute in body", "meta": {}, "source": { "header": "Authorization", "parameter": "limit", "pointer": "/data/attributes/title" }, "status": "400", "title": "Bad Request" } ] } ``` {% /tab %} {% /tab %} {% tab title="403" %} Forbidden {% tab title="Model" %} API error response. | Parent field | Field | Type | Description | | ------------ | ------------------------ | -------- | ------------------------------------------------------------------------------- | | | errors [*required*] | [object] | A list of errors. | | errors | detail | string | A human-readable explanation specific to this occurrence of the error. | | errors | meta | object | Non-standard meta-information about the error | | errors | source | object | References to the source of the error. | | source | header | string | A string indicating the name of a single request header which caused the error. | | source | parameter | string | A string indicating which URI query parameter caused the error. | | source | pointer | string | A JSON pointer to the value in the request document that caused the error. | | errors | status | string | Status code of the response. | | errors | title | string | Short human-readable summary of the error. | {% /tab %} {% tab title="Example" %} ```json { "errors": [ { "detail": "Missing required attribute in body", "meta": {}, "source": { "header": "Authorization", "parameter": "limit", "pointer": "/data/attributes/title" }, "status": "400", "title": "Bad Request" } ] } ``` {% /tab %} {% /tab %} {% tab title="404" %} Not Found {% tab title="Model" %} API error response. | Parent field | Field | Type | Description | | ------------ | ------------------------ | -------- | ------------------------------------------------------------------------------- | | | errors [*required*] | [object] | A list of errors. | | errors | detail | string | A human-readable explanation specific to this occurrence of the error. | | errors | meta | object | Non-standard meta-information about the error | | errors | source | object | References to the source of the error. | | source | header | string | A string indicating the name of a single request header which caused the error. | | source | parameter | string | A string indicating which URI query parameter caused the error. | | source | pointer | string | A JSON pointer to the value in the request document that caused the error. | | errors | status | string | Status code of the response. | | errors | title | string | Short human-readable summary of the error. | {% /tab %} {% tab title="Example" %} ```json { "errors": [ { "detail": "Missing required attribute in body", "meta": {}, "source": { "header": "Authorization", "parameter": "limit", "pointer": "/data/attributes/title" }, "status": "400", "title": "Bad Request" } ] } ``` {% /tab %} {% /tab %} {% tab title="429" %} Too many requests {% tab title="Model" %} API error response. | Field | Type | Description | | ------------------------ | -------- | ----------------- | | errors [*required*] | [string] | A list of errors. | {% /tab %} {% tab title="Example" %} ```json { "errors": [ "Bad Request" ] } ``` {% /tab %} {% /tab %} {% tab title="500" %} Internal Server Error {% tab title="Model" %} API error response. | Parent field | Field | Type | Description | | ------------ | ------------------------ | -------- | ------------------------------------------------------------------------------- | | | errors [*required*] | [object] | A list of errors. | | errors | detail | string | A human-readable explanation specific to this occurrence of the error. | | errors | meta | object | Non-standard meta-information about the error | | errors | source | object | References to the source of the error. | | source | header | string | A string indicating the name of a single request header which caused the error. | | source | parameter | string | A string indicating which URI query parameter caused the error. | | source | pointer | string | A JSON pointer to the value in the request document that caused the error. | | errors | status | string | Status code of the response. | | errors | title | string | Short human-readable summary of the error. | {% /tab %} {% tab title="Example" %} ```json { "errors": [ { "detail": "Missing required attribute in body", "meta": {}, "source": { "header": "Authorization", "parameter": "limit", "pointer": "/data/attributes/title" }, "status": "400", "title": "Bad Request" } ] } ``` {% /tab %} {% /tab %} ### Code Example ##### \# Path parameters export experiment_id="3fd6b5e0-8910-4b1c-a7d0-5b84de329012" \# Curl command curl -X GET "https://api.datadoghq.com/api/v2/llm-obs/v3/experiments/${experiment_id}/events" \ -H "Accept: application/json" \ -H "DD-API-KEY: ${DD_API_KEY}" \ -H "DD-APPLICATION-KEY: ${DD_APP_KEY}" {% /tab %}