types

MCP Protocol Types

JSON-RPC 2.0 and MCP specification compliant data structures

Fully compatible with FastMCP and other MCP implementations
Standard OAuth 2.1 Bearer token authentication support
Comprehensive tool, memory, and capability definitions

Structs

`JsonRpcRequest`

JSON-RPC 2.0 Request - Standard wire format for MCP

Fields

Field	Type	Description
`jsonrpc`	`String`	JSON-RPC version (always “2.0”)
`id`	`Option<serde_json::Value>`	Request ID (optional for notifications)
`method`	`String`	Method name (e.g., “tools/list”, “tools/call”)
`params`	`Option<serde_json::Value>`	Method parameters (optional)

Methods

`new`

fn new(method: &str, params: Option<serde_json::Value>, id: Option<serde_json::Value>) -> Self

Create new JSON-RPC request

`notification`

fn notification(method: &str, params: Option<serde_json::Value>) -> Self

Create notification (no response expected)

`with_id`

fn with_id(method: &str, params: Option<serde_json::Value>, id: &str) -> Self

Create request with string ID

`JsonRpcResponse`

JSON-RPC 2.0 Response - Standard response format

Fields

Field	Type	Description
`jsonrpc`	`String`	JSON-RPC version (always “2.0”)
`id`	`Option<serde_json::Value>`	Response ID (matches request ID)
`result`	`Option<serde_json::Value>`	Success result (mutually exclusive with error)
`error`	`Option<JsonRpcError>`	Error information (mutually exclusive with result)

Methods

`success`

fn success(id: Option<serde_json::Value>, result: serde_json::Value) -> Self

Create success response

`error`

fn error(id: Option<serde_json::Value>, error: JsonRpcError) -> Self

Create error response

`JsonRpcError`

JSON-RPC 2.0 Error - Standard error format

Fields

Field	Type	Description
`code`	`i32`	Error code (standard JSON-RPC error codes)
`message`	`String`	Error message
`data`	`Option<serde_json::Value>`	Additional error data (optional)

Methods

`method_not_found`

fn method_not_found(message: &str) -> Self

Method not found (-32601)

`invalid_params`

fn invalid_params(message: &str) -> Self

Invalid params (-32602)

`internal_error`

fn internal_error(message: &str) -> Self

Internal error (-32603)

`InitializeRequest`

Initialize Request - MCP handshake

Fields

Field	Type	Description
`protocol_version`	`String`	Protocol version requested by client
`capabilities`	`ClientCapabilities`	Client capabilities
`client_info`	`ClientInfo`	Client information

`InitializeResult`

Initialize Result - MCP handshake response

Fields

Field	Type	Description
`protocol_version`	`String`	Protocol version supported by server
`capabilities`	`ServerCapabilities`	Server capabilities
`server_info`	`ServerInfo`	Server information

`ClientInfo`

Client Information

Fields

Field	Type	Description
`name`	`String`	Client name
`version`	`String`	Client version
`description`	`Option<String>`	Client description (optional)

`ServerInfo`

Server Information

Fields

Field	Type	Description
`name`	`String`	Server name
`version`	`String`	Server version
`description`	`Option<String>`	Server description (optional)

`ClientCapabilities`

Client Capabilities

Fields

Field	Type	Description
`tools`	`Option<ToolCapabilities>`	Tool execution support

`ServerCapabilities`

Server Capabilities

Fields

Field	Type	Description
`tools`	`Option<ToolCapabilities>`	Tool execution support

`ToolCapabilities`

Tool Capabilities

Fields

Field	Type	Description
`supported`	`bool`	Tool listing support

`ListToolsResult`

List Tools Result

Fields

Field	Type	Description
`tools`	`Vec<Tool>`	Available tools

`Tool`

Tool Definition

Fields

Field	Type	Description
`name`	`String`	Tool name
`description`	`String`	Tool description
`input_schema`	`serde_json::Value`	JSON Schema for tool parameters

Methods

`simple`

fn simple(name: &str, description: &str, parameters: &[&str]) -> Self

Create simple tool with string parameters

`CallToolRequest`

Call Tool Request

Fields

Field	Type	Description
`name`	`String`	Tool name to execute
`arguments`	`Option<serde_json::Value>`	Tool arguments
`meta`	`Option<serde_json::Value>`	Optional MCP request metadata.

`CallToolResult`

Call Tool Result

Fields

Field	Type	Description
`content`	`Vec<Content>`	Tool execution result content
`is_error`	`Option<bool>`	Whether execution resulted in error

`BearerToken`

Bearer Token Authentication

Fields

Field	Type	Description
`access_token`	`String`	OAuth 2.1 access token
`token_type`	`String`	Token type (always “Bearer”)

Methods

`new`

fn new(access_token: &str) -> Self

Create new bearer token

`to_authorization_header`

fn to_authorization_header(&self) -> String

Format as Authorization header value

Enums

`Content`

Content - Multi-modal content representation

Variants

Variant	Description
`Text { ... }`

Methods

`text`

fn text(text: &str) -> Self

Create text content