Module types 

MCP Protocol Types

This module contains all the type definitions for the Model Context Protocol according to the 2025-06-18 specification.

Modules

error_codes

Standard JSON-RPC error codes per specification

Structs

Annotations

General annotations that can be attached to various MCP objects

ArgumentInfo

Information about the argument being completed

AudioContent

Audio content per MCP 2025-06-18 specification

BaseMetadata

Base interface for metadata with name (identifier) and title (display name) properties. Per MCP specification 2025-06-18, this is the foundation for Tool, Resource, and Prompt metadata.

BlobResourceContents

Binary resource contents

CallToolRequest

Call tool request

CallToolResult

Call tool result

CancelledNotification

Cancellation notification per MCP 2025-06-18 specification

ClientCapabilities

Client capabilities per MCP 2025-06-18 specification

CompleteRequest

Request for argument completion

CompleteRequestParams

Parameters for completion/complete request

CompleteResult

Server’s response to a completion request

CompletionCapabilities

Completion capabilities

CompletionContext

Context for completion requests

CompletionResponse

Completion response information

CreateMessageRequest

Create message request

CreateMessageResult

Create message result

ElicitRequest

Request to elicit user input (server-initiated)

ElicitRequestParams

Parameters for elicitation/create request

ElicitResult

Client’s response to an elicitation request

ElicitationCapabilities

Elicitation capabilities

ElicitationSchema

Elicitation schema - restricted subset of JSON Schema for primitive types only

EmbeddedResource

Embedded resource content per MCP 2025-06-18 specification

EmptyResult

Empty result for operations that don’t return data

GetPromptRequest

Get prompt request

GetPromptResult

Get prompt result

ImageContent

Image content per MCP 2025-06-18 specification

Implementation

Implementation information for MCP clients and servers

InitializeRequest

Initialize request

InitializeResult

Initialize result

InitializedNotification

Initialized notification (no parameters)

JsonRpcError

JSON-RPC error structure per MCP 2025-06-18 specification

ListPromptsRequest

List prompts request (no parameters)

ListPromptsResult

List prompts result

ListResourceTemplatesParams

Parameters for listing resource templates

ListResourceTemplatesRequest

Request to list resource templates

ListResourceTemplatesResult

Result of listing resource templates

ListResourcesRequest

List resources request

ListResourcesResult

List resources result

ListRootsRequest

List roots request (no parameters)

ListRootsResult

List roots result

ListToolsRequest

List tools request (no parameters)

ListToolsResult

List tools result

LoggingCapabilities

Logging capabilities

LoggingNotification

Logging notification

ModelHint

Model hint

ModelPreferences

Model preferences

PingParams

Parameters for ping requests

PingRequest

A ping request to check connection health

PingResult

Response to a ping request (usually empty)

ProgressNotification

Progress notification per MCP 2025-06-18 specification

Prompt

Prompt definition per MCP 2025-06-18 specification

PromptArgument

Prompt argument definition per MCP 2025-06-18 specification

PromptMessage

Prompt message

PromptReference

Reference to a prompt for completion

PromptReferenceData

Data for prompt reference (excluding the type field)

PromptsCapabilities

Prompts capabilities

ReadResourceRequest

Read resource request

ReadResourceResult

Read resource result

Resource

Resource definition per MCP 2025-06-18 specification

ResourceContents

Base resource contents interface

ResourceLink

Resource link per MCP 2025-06-18 specification

ResourceTemplate

A template description for resources available on the server Supports RFC 6570 URI template expansion

ResourceTemplateReference

Reference to a resource template for completion

ResourceTemplateReferenceData

Data for resource template reference (excluding the type field)

ResourceUpdatedNotification

Resource updated notification

ResourcesCapabilities

Resources capabilities

Root

Filesystem root

RootsCapabilities

Roots capabilities

RootsListChangedNotification

Roots list changed notification (no parameters)

SamplingCapabilities

Sampling capabilities

SamplingMessage

Sampling message

ServerCapabilities

Server capabilities per MCP 2025-06-18 specification

SetLevelRequest

Set log level request

SetLevelResult

Set log level result (no data)

SubscribeRequest

Subscribe to resource request

TextContent

Text content per MCP 2025-06-18 specification

TextResourceContents

Text resource contents

Tool

Tool definition per MCP 2025-06-18 specification

ToolAnnotations

Tool-specific annotations for additional tool information

ToolInputSchema

Tool input schema definition

ToolOutputSchema

Tool output schema definition

ToolsCapabilities

Tools capabilities

UnsubscribeRequest

Unsubscribe from resource request

Enums

ClientNotification

Client-initiated notification

ClientRequest

Client-initiated request

CompletionReference

Reference types for completion requests

ContentBlock

Content block union type per MCP 2025-06-18 specification

ElicitationAction

Action taken by user in response to elicitation

IncludeContext

Include context options

LogLevel

Log level

PrimitiveSchemaDefinition

Primitive schema definition for elicitation requests Only allows primitive types without nesting, as per MCP 2025-06-18 spec

ResourceContent

Union type for resource contents (text or binary)

Role

Role in conversation

ServerNotification

Server-initiated notification

ServerRequest

Server-initiated request

Type Aliases

Base64String

Base64 encoded data

Content

Compatibility alias for the old Content enum

Cursor

Cursor for pagination

MimeType

MIME type

ProgressToken

Progress token for tracking long-running operations

PromptInput

Prompt input parameters

ProtocolVersion

Protocol version string

RequestId

JSON-RPC request identifier

Uri

URI string