> ## Documentation Index
> Fetch the complete documentation index at: https://wb-21fd5541-docs-1917.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Call schema reference

> Reference for the Call object structure and properties

This page provides a reference for the Call object schema in W\&B Weave. For information on querying calls, see [Query and export calls](/weave/guides/tracking/querying-calls).

## Call properties

The table below outlines the key properties of a Call in Weave. For the complete implementation, see:

* [class: CallSchema](/weave/reference/python-sdk/trace_server/trace_server_interface#class-callschema) in the Python SDK.
* [Interface: CallSchema](/weave/reference/typescript-sdk/interfaces/callschema) in the TypeScript SDK.

| Property       | Type                  | Description                                                                                        |
| -------------- | --------------------- | -------------------------------------------------------------------------------------------------- |
| `id`           | string (uuid)         | Unique identifier for the call                                                                     |
| `project_id`   | string (optional)     | Associated project identifier                                                                      |
| `op_name`      | string                | Name of the operation (can be a reference)                                                         |
| `display_name` | string (optional)     | User-friendly name for the call                                                                    |
| `trace_id`     | string (uuid)         | Identifier for the trace this call belongs to                                                      |
| `parent_id`    | string (uuid)         | Identifier of the parent call                                                                      |
| `started_at`   | datetime              | Timestamp when the call started                                                                    |
| `attributes`   | Dict\[str, Any]       | User-defined metadata about the call *(read-only during execution)*                                |
| `inputs`       | Dict\[str, Any]       | Input parameters for the call                                                                      |
| `ended_at`     | datetime (optional)   | Timestamp when the call ended                                                                      |
| `exception`    | string (optional)     | Error message if the call failed                                                                   |
| `output`       | Any (optional)        | Result of the call                                                                                 |
| `summary`      | Optional\[SummaryMap] | Post-execution summary information. You can modify this during execution to record custom metrics. |
| `wb_user_id`   | Optional\[str]        | Associated W\&B user ID                                                                            |
| `wb_run_id`    | Optional\[str]        | Associated W\&B run ID                                                                             |
| `deleted_at`   | datetime (optional)   | Timestamp of call deletion, if applicable                                                          |

## Property details

`CallSchema` properties play an important role in tracking and managing function calls:

* The `id`, `trace_id`, and `parent_id` properties help organize and relate calls within the system.

* Timing information (`started_at`, `ended_at`) support performance analysis.

* The `attributes` and `inputs` properties provide context for the call. Attributes are frozen once the call starts, so set them before invocation with `weave.attributes`. `output` and `summary` capture the results.
  -You can store metrics or other post-call values in the `summary` property. Modify `call.summary` during execution. Any values you add is merged with Weave's computed summary data when the Call finishes.
  * Weave's computed summary data:
    * `costs`: The total cost of the call based on LLM model usage data and token pricing data.  For more information on cost calculation, see [Track costs](/weave/guides/tracking/costs).
    * `latency_ms`: The duration, in milliseconds, elapsed between `started_at` and `ended_at`. `null` if `status` is `RUNNING`.
    * `status`: The execution status: `SUCCESS`, `ERROR`, `RUNNING`, `DESCENDANT_ERROR` (meaning the call itself succeeded but a descendant call errored). {/* [empty ref](/weave/reference/python-sdk/trace_server/trace_server_interface#class-tracestatus)*/}

* Integration with W\&B is facilitated through `wb_user_id` and `wb_run_id`.

This comprehensive set of properties enables detailed tracking and analysis of function calls throughout your project.