Class McpNotificationLogger

MCP Notification Logger

Sends structured log messages to MCP clients via the notifications/message protocol. Clients that support the logging capability will receive and display these messages.

Features:

Multi-server support for multi-session scenarios
Level filtering with configurable minimum level
Secret scrubbing for security
Context-aware logger creation for tool handlers

Example

// Set up with MCP server
mcpLogger.addServer(mcpServer);

// Log messages (sent to all connected clients)
await mcpLogger.info('Processing request...');
await mcpLogger.warn('Resource limit approaching', { current: 80, max: 100 });
await mcpLogger.error('Failed to connect', { error: 'Connection refused' });

Constructors

constructor

new McpNotificationLogger(config?: McpLoggerConfig): McpNotificationLogger
Create a new McpNotificationLogger.
Parameters
- config: McpLoggerConfig = {}
  Optional configuration
Returns McpNotificationLogger
- Defined in src/logger/mcp-logger.ts:109

Methods

addHandler

addHandler(handler: LogNotificationHandler): void
Register a notification handler for receiving log notifications. Multiple handlers can be registered for multi-session scenarios.
Parameters
- handler: LogNotificationHandler
  The notification handler to register
Returns void
- Defined in src/logger/mcp-logger.ts:124

alert

alert(message: string, data?: Record<string, unknown>): Promise<void>
Log an alert message
Parameters
- message: string
- Optionaldata: Record<string, unknown>
Returns Promise<void>
- Defined in src/logger/mcp-logger.ts:272

clearHandlers

clearHandlers(): void
Clear all registered handlers.

Returns void
- Defined in src/logger/mcp-logger.ts:146

createContextLogger

createContextLogger(
handler: LogNotificationHandler,
): (level: LogLevel, message: string) => void
Create a context-aware logger function for use in tool handlers. Returns a function that can be passed to LogContext.sendMcpLog.
Parameters
- handler: LogNotificationHandler
  The notification handler for this context
Returns (level: LogLevel, message: string) => void
A function compatible with LogContext.sendMcpLog
Example
```
const sendMcpLog = mcpLogger.createContextLogger(handler);
logger.runWithContext({ sendMcpLog }, () => {
  logger.info('This will also be sent to MCP client');
});
```
- Defined in src/logger/mcp-logger.ts:300

critical

critical(message: string, data?: Record<string, unknown>): Promise<void>
Log a critical message
Parameters
- message: string
- Optionaldata: Record<string, unknown>
Returns Promise<void>
- Defined in src/logger/mcp-logger.ts:267

debug

debug(message: string, data?: Record<string, unknown>): Promise<void>
Log a debug message
Parameters
- message: string
- Optionaldata: Record<string, unknown>
Returns Promise<void>
- Defined in src/logger/mcp-logger.ts:237

emergency

emergency(message: string, data?: Record<string, unknown>): Promise<void>
Log an emergency message
Parameters
- message: string
- Optionaldata: Record<string, unknown>
Returns Promise<void>
- Defined in src/logger/mcp-logger.ts:277

error

error(message: string, data?: Record<string, unknown>): Promise<void>
Log an error message
Parameters
- message: string
- Optionaldata: Record<string, unknown>
Returns Promise<void>
- Defined in src/logger/mcp-logger.ts:262

getHandlerCount

getHandlerCount(): number
Get the number of registered handlers.

Returns number
- Defined in src/logger/mcp-logger.ts:154

getMinLevel

getMinLevel(): McpLogLevel
Get the current minimum log level.

Returns McpLogLevel
- Defined in src/logger/mcp-logger.ts:192

info

info(message: string, data?: Record<string, unknown>): Promise<void>
Log an info message
Parameters
- message: string
- Optionaldata: Record<string, unknown>
Returns Promise<void>
- Defined in src/logger/mcp-logger.ts:242

isAvailable

isAvailable(): boolean
Check if logging is currently available (enabled and has servers).

Returns boolean
- Defined in src/logger/mcp-logger.ts:199

isEnabled

isEnabled(): boolean
Check if logging is enabled.

Returns boolean
- Defined in src/logger/mcp-logger.ts:175

log

log(
    level: McpLogLevel,
    message: string,
    data?: Record<string, unknown>,
): Promise<void>
Send a log message to all connected MCP clients.
Parameters
- level: McpLogLevel
  The MCP log level
- message: string
  The log message
- Optionaldata: Record<string, unknown>
  Optional structured data to include
Returns Promise<void>
Promise that resolves when all sends complete
- Defined in src/logger/mcp-logger.ts:215

notice

notice(message: string, data?: Record<string, unknown>): Promise<void>
Log a notice message
Parameters
- message: string
- Optionaldata: Record<string, unknown>
Returns Promise<void>
- Defined in src/logger/mcp-logger.ts:247

removeHandler

removeHandler(handler: LogNotificationHandler): void
Unregister a notification handler.
Parameters
- handler: LogNotificationHandler
  The notification handler to remove
Returns void
- Defined in src/logger/mcp-logger.ts:136

setEnabled

setEnabled(enabled: boolean): void
Enable or disable MCP logging. When disabled, log methods become no-ops but still return resolved promises.
Parameters
- enabled: boolean
  Whether to enable logging
Returns void
- Defined in src/logger/mcp-logger.ts:168

setMinLevel

setMinLevel(level: McpLogLevel): void
Set the minimum log level. Messages below this level will not be sent.
Parameters
- level: McpLogLevel
  The minimum log level
Returns void
- Defined in src/logger/mcp-logger.ts:185

warn

warn(message: string, data?: Record<string, unknown>): Promise<void>
Log a warning message
Parameters
- message: string
- Optionaldata: Record<string, unknown>
Returns Promise<void>
- Defined in src/logger/mcp-logger.ts:252

warning

warning(message: string, data?: Record<string, unknown>): Promise<void>
Log a warning message (alias for warn)
Parameters
- message: string
- Optionaldata: Record<string, unknown>
Returns Promise<void>
- Defined in src/logger/mcp-logger.ts:257

Class McpNotificationLogger

Example

Index

Constructors

Methods

Constructors

constructor

Parameters

Returns McpNotificationLogger

Methods

addHandler

Parameters

Returns void

alert

Parameters

Returns Promise<void>

clearHandlers

Returns void

createContextLogger

Parameters

Returns (level: LogLevel, message: string) => void

Example

critical

Parameters

Returns Promise<void>

debug

Parameters

Returns Promise<void>

emergency

Parameters

Returns Promise<void>

error

Parameters

Returns Promise<void>

getHandlerCount

Returns number

getMinLevel

Returns McpLogLevel

info

Parameters

Returns Promise<void>

isAvailable

Returns boolean

isEnabled

Returns boolean

log

Parameters

Returns Promise<void>

notice

Parameters

Returns Promise<void>

removeHandler

Parameters

Returns void

setEnabled

Parameters

Returns void

setMinLevel

Parameters

Returns void

warn

Parameters

Returns Promise<void>

warning

Parameters

Returns Promise<void>

Settings

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