> ## Documentation Index
> Fetch the complete documentation index at: https://ai.easyaf.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# EdmPayloadValidator

> Validates tool payloads against the declared EDM before any OData HTTP is sent, and formats values for the wire.

## Definition

**Assembly:** Microsoft.OData.Mcp.Core.dll

**Namespace:** Microsoft.OData.Mcp.Core.Catalog

**Inheritance:** System.Object

## Syntax

```csharp theme={null}
Microsoft.OData.Mcp.Core.Catalog.EdmPayloadValidator
```

## Summary

Validates tool payloads against the declared EDM before any OData HTTP is sent, and formats values for the wire.

## Remarks

This is how the first `tools/call` becomes the right one: a wrong JSON kind, an unknown property, a missing
required-on-create value, an enum member that does not exist, or a string over `MaxLength` is reported with
the declared shape instead of a round trip to the service. Every rule here is OPTIMIZATION.md §4 and §5.

## Methods

###  DescribeExpected

Describes the JSON the EDM type expects, for error messages.

#### Syntax

```csharp theme={null}
public static string DescribeExpected(Microsoft.OData.Mcp.Core.Models.EdmModel model, string edmType)
```

#### Parameters

| Name | Type | Description |
| - | - | - |
| `model` | `Microsoft.OData.Mcp.Core.Models.EdmModel` | The Core EDM. |
| `edmType` | `string` | The EDM type name. |

#### Returns

Type: `string`
Text such as `a JSON number` or `one of Red, Green`.

#### Exceptions

| Exception | Description |
| - | - |
| `ArgumentNullException` | Thrown when *model* is null. |

###  FormatUrlLiteral

Formats a primitive or enumeration argument as an OData URL literal for a function call.

#### Syntax

```csharp theme={null}
public static string FormatUrlLiteral(Microsoft.OData.Mcp.Core.Models.EdmModel model, string edmType, System.Text.Json.JsonElement value)
```

#### Parameters

| Name | Type | Description |
| - | - | - |
| `model` | `Microsoft.OData.Mcp.Core.Models.EdmModel` | The Core EDM. |
| `edmType` | `string` | The parameter's EDM type. |
| `value` | `System.Text.Json.JsonElement` | The validated JSON value. |

#### Returns

Type: `string?`
The literal (for example `'open'`, `33`, `NS.Color'Red'`, `duration'P1D'`), or `null` when the
value must travel as a parameter alias (complex types, collections, entities).

#### Exceptions

| Exception | Description |
| - | - |
| `ArgumentNullException` | Thrown when *model* is null. |

###  NormalizeBodyValue

Converts a validated argument to the value written into an action's JSON body.

#### Syntax

```csharp theme={null}
public static object NormalizeBodyValue(Microsoft.OData.Mcp.Core.Models.EdmModel model, string edmType, System.Text.Json.JsonElement value)
```

#### Parameters

| Name | Type | Description |
| - | - | - |
| `model` | `Microsoft.OData.Mcp.Core.Models.EdmModel` | The Core EDM. |
| `edmType` | `string` | The parameter's EDM type. |
| `value` | `System.Text.Json.JsonElement` | The validated JSON value. |

#### Returns

Type: `object?`
The member name for enumerations given as numbers or OData literals; otherwise the element unchanged.

#### Exceptions

| Exception | Description |
| - | - |
| `ArgumentNullException` | Thrown when *model* is null. |

###  ValidateEntityBody

Validates a create or update body against the declared type.

#### Syntax

```csharp theme={null}
public static string ValidateEntityBody(Microsoft.OData.Mcp.Core.Models.EdmModel model, Microsoft.OData.Mcp.Core.Catalog.ODataMcpCatalogOptions options, Microsoft.OData.Mcp.Core.Catalog.EdmTypeShape shape, System.Text.Json.JsonElement body, bool isCreate)
```

#### Parameters

| Name | Type | Description |
| - | - | - |
| `model` | `Microsoft.OData.Mcp.Core.Models.EdmModel` | The Core EDM. |
| `options` | `Microsoft.OData.Mcp.Core.Catalog.ODataMcpCatalogOptions` | Catalog options (required-on-create enforcement, enum wire format). |
| `shape` | `Microsoft.OData.Mcp.Core.Catalog.EdmTypeShape` | The target type's shape. |
| `body` | `System.Text.Json.JsonElement` | The parsed JSON object. |
| `isCreate` | `bool` | `true` for POST, which also checks required-on-create; `false` for PATCH. |

#### Returns

Type: `string?`
`null` when the body is valid; otherwise the message the caller returns as a tool error.

#### Exceptions

| Exception | Description |
| - | - |
| `ArgumentNullException` | Thrown when *model*, *options*, or *shape* is null. |

#### Remarks

Checks, in order: required-on-create (POST only, unless [ODataMcpCatalogOptions.EnforceRequiredOnCreate](https://ai.easyaf.dev/odata-mcp/api-reference/Microsoft/OData/Mcp/Core/Catalog/ODataMcpCatalogOptions.md#enforcerequiredoncreate)
is off), unknown properties on closed types, JSON kind per EDM type, `null` for non-nullable properties, enum
membership, and `MaxLength`. Keys containing `@` (annotations, `Nav@odata.bind`) and navigation
property names (deep insert) are passed through.

###  ValidateOperationArguments

Validates the `parameters` object of an `odata_call` against the operation's declared parameters.

#### Syntax

```csharp theme={null}
public static string ValidateOperationArguments(Microsoft.OData.Mcp.Core.Models.EdmModel model, Microsoft.OData.Mcp.Core.Catalog.ODataMcpCatalogOptions options, System.Collections.Generic.IReadOnlyList<Microsoft.OData.Mcp.Core.Models.EdmParameter> parameters, bool isBound, System.Nullable<System.Text.Json.JsonElement> arguments, string signature, out System.Collections.Generic.List<System.Collections.Generic.KeyValuePair<Microsoft.OData.Mcp.Core.Models.EdmParameter, System.Text.Json.JsonElement>> values)
```

#### Parameters

| Name | Type | Description |
| - | - | - |
| `model` | `Microsoft.OData.Mcp.Core.Models.EdmModel` | The Core EDM. |
| `options` | `Microsoft.OData.Mcp.Core.Catalog.ODataMcpCatalogOptions` | Catalog options (enum wire format). |
| `parameters` | `System.Collections.Generic.IReadOnlyList<Microsoft.OData.Mcp.Core.Models.EdmParameter>` | The declared parameters, including the binding parameter when bound. |
| `isBound` | `bool` | Whether the first declared parameter is the binding parameter. |
| `arguments` | `System.Nullable<System.Text.Json.JsonElement>` | The caller's `parameters` object, or `null` when omitted. |
| `signature` | `string` | The rendered signature, appended to errors. |
| `values` | `System.Collections.Generic.List<System.Collections.Generic.KeyValuePair<Microsoft.OData.Mcp.Core.Models.EdmParameter, System.Text.Json.JsonElement>>` | Receives the accepted arguments keyed by declared parameter name, in declaration order. |

#### Returns

Type: `string?`
`null` when every argument is declared, required ones are present, and kinds match; otherwise the error message.

#### Exceptions

| Exception | Description |
| - | - |
| `ArgumentNullException` | Thrown when *model*, *options*, or *parameters* is null. |

#### Remarks

Names match by exact spelling; there is no fuzzy matching. Passing the binding parameter is an unknown-parameter error.

### &#x20;ValidateOperationArguments

Validates non-binding operation arguments against the declared parameters.

#### Syntax

```csharp theme={null}
public static string ValidateOperationArguments(Microsoft.OData.Mcp.Core.Models.EdmModel model, Microsoft.OData.Mcp.Core.Catalog.ODataMcpCatalogOptions options, System.Collections.Generic.IReadOnlyList<Microsoft.OData.Mcp.Core.Models.EdmParameter> parameters, bool isBound, System.Collections.Generic.IReadOnlyDictionary<string, System.Text.Json.JsonElement> arguments, string signature, out System.Collections.Generic.List<System.Collections.Generic.KeyValuePair<Microsoft.OData.Mcp.Core.Models.EdmParameter, System.Text.Json.JsonElement>> values)
```

#### Parameters

| Name | Type | Description |
| - | - | - |
| `model` | `Microsoft.OData.Mcp.Core.Models.EdmModel` | The Core EDM. |
| `options` | `Microsoft.OData.Mcp.Core.Catalog.ODataMcpCatalogOptions` | Catalog options (enum wire format). |
| `parameters` | `System.Collections.Generic.IReadOnlyList<Microsoft.OData.Mcp.Core.Models.EdmParameter>` | The declared parameters, including the binding parameter when bound. |
| `isBound` | `bool` | Whether the first declared parameter is the binding parameter. |
| `arguments` | `System.Collections.Generic.IReadOnlyDictionary<string, System.Text.Json.JsonElement>` | The caller arguments keyed by declared parameter name, or `null` when omitted. |
| `signature` | `string` | The rendered signature, appended to errors. |
| `values` | `System.Collections.Generic.List<System.Collections.Generic.KeyValuePair<Microsoft.OData.Mcp.Core.Models.EdmParameter, System.Text.Json.JsonElement>>` | Receives the accepted arguments keyed by declared parameter name, in declaration order. |

#### Returns

Type: `string?`
`null` when every argument is declared, required ones are present, and kinds match; otherwise the error message.

#### Exceptions

| Exception | Description |
| - | - |
| `ArgumentNullException` | Thrown when *model*, *options*, or *parameters* is null. |

#### Remarks

Names match by exact spelling; there is no fuzzy matching. Passing the binding parameter is an unknown-parameter error.

### &#x20;ValidateValue

Validates one JSON value against an EDM type.

#### Syntax

```csharp theme={null}
public static string ValidateValue(Microsoft.OData.Mcp.Core.Models.EdmModel model, Microsoft.OData.Mcp.Core.Catalog.ODataMcpCatalogOptions options, string edmType, bool nullable, System.Nullable<int> maxLength, System.Text.Json.JsonElement value, string label)
```

#### Parameters

| Name | Type | Description |
| - | - | - |
| `model` | `Microsoft.OData.Mcp.Core.Models.EdmModel` | The Core EDM. |
| `options` | `Microsoft.OData.Mcp.Core.Catalog.ODataMcpCatalogOptions` | Catalog options (enum wire format). |
| `edmType` | `string` | The EDM type name, possibly `Collection(...)`. |
| `nullable` | `bool` | Whether JSON `null` is acceptable. |
| `maxLength` | `System.Nullable<int>` | The declared `MaxLength` for strings, or `null`. |
| `value` | `System.Text.Json.JsonElement` | The JSON value. |
| `label` | `string` | How to name the value in errors, for example `Parameter 'lat'` or `Property 'Age' on Person`. |

#### Returns

Type: `string?`
`null` when the value fits; otherwise a sentence ending in a period.

#### Exceptions

| Exception | Description |
| - | - |
| `ArgumentNullException` | Thrown when *model* or *options* is null. |


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