Class MissingRequiredClientCapabilityException

Namespace

ModelContextProtocol

Assembly

ModelContextProtocol.Core.dll

Represents an exception used to signal that a request requires a client capability that was not declared in the request's per-request _meta/io.modelcontextprotocol/clientCapabilities field.

public sealed class MissingRequiredClientCapabilityException : McpProtocolException, ISerializable

Inheritance

object

Exception

McpException

McpProtocolException

MissingRequiredClientCapabilityException

Implements

ISerializable

Inherited Members

McpProtocolException.ErrorCode

Exception.GetBaseException()

Exception.GetType()

Exception.ToString()

Exception.Data

Exception.HelpLink

Exception.HResult

Exception.InnerException

Exception.Message

Exception.Source

Exception.StackTrace

Exception.TargetSite

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.ReferenceEquals(object, object)

Remarks

Introduced by the 2026-07-28 protocol revision (SEP-2575). Servers throw this exception when a handler cannot proceed because the client did not declare a required capability for the request. The exception is converted to a JSON-RPC error response with code MissingRequiredClientCapability (-32021) and a MissingRequiredClientCapabilityErrorData payload.

Constructors

MissingRequiredClientCapabilityException(ClientCapabilities, string?)

Initializes a new instance of the MissingRequiredClientCapabilityException class.

public MissingRequiredClientCapabilityException(ClientCapabilities requiredCapabilities, string? message = null)

Parameters

requiredCapabilities ClientCapabilities

The capabilities the server requires for the request.

message string

A human-readable description of the error. If null, a default message is used.

Properties

RequiredCapabilities

Gets the client capabilities required for the request.

public ClientCapabilities RequiredCapabilities { get; }

Property Value

ClientCapabilities