# ContextWindowEstimate

> Tracon documentation. Tracon is a .NET package family that adds a control
> plane on Microsoft Agent Framework, published as NuGet packages that run
> inside your own ASP.NET Core application.
>
> Page: https://tracon.dev/http-api/schemas/contextwindowestimate/
> Summary: OpenAPI request or response schema for ContextWindowEstimate, including required fields, defaults, constraints, and linked nested types.

[← All HTTP schemas](/http-api/schemas/)

The result of a pre-flight context-window check, computed without calling
the model provider.

**Shape:** `object`

| Property | Required | Type | Description | Rules |
|---|---|---|---|---|
| `promptTokens` | yes | `integer (int32)` | Gets the estimated token count of the prompt. The estimate is approximate. | pattern `^-?(?:0\\|[1-9]\d*)$` |
| `contextWindowTokens` | yes | `integer (int32)` | Gets the model's context window size, taken from the model catalog's `ModelDescriptor.ContextWindowTokens`. `null` when the model is not found in the catalog. | pattern `^-?(?:0\\|[1-9]\d*)$` |
| `allowedPromptTokens` | yes | `integer (int32)` | Gets the token budget kept for the prompt after `TraconPreflightOptions.ReserveRatio` is set aside for the answer. `null` when `ContextWindowTokens` is unknown. | pattern `^-?(?:0\\|[1-9]\d*)$` |
| `wouldBeRejected` | yes | `boolean` | Gets whether a real run with this prompt would be rejected by the pre-flight check. Always `false` when `ContextWindowTokens` is unknown — an unknown window can never be exceeded. | — |