adk_mcp 2026.3.1

MCP protocol client primitives for ADK Dart packages.

adk_mcp

adk_mcp provides MCP (Model Context Protocol) client primitives for Dart.

It includes:

• Streamable HTTP MCP client (McpRemoteClient)
• stdio MCP client (McpStdioClient)
• MCP constants, method names, protocol version handling, and JSON-RPC helpers

Feature Support Matrix (Current)

Status legend:

• ✅ Supported
• ⚠️ Partial / integration required
• ❌ Not supported yet

Supported / Working

Area	Feature	Status	Notes
Transport	Streamable HTTP MCP client	✅	JSON-RPC call/notify with initialize handshake support.
Transport	stdio MCP client	✅	Child-process based JSON-RPC transport.
Protocol	MCP protocol version negotiation	✅	Supports 2025-03-26, 2025-06-18, 2025-11-25.
RPC helpers	Tools/resources/prompts/tasks/logging/sampling/roots/elicitation method helpers	✅	High-level helper methods are provided for client calls.
Paging	Cursor-based pagination helper (collectPaginatedMaps)	✅	Works for both HTTP and stdio clients.
Server events	Server notification/request callback hooks	✅	onServerMessage / onServerRequest are supported.
Session	HTTP session termination helper	✅	terminateSession() sends MCP DELETE termination request.

Partial / Not Yet Supported

Area	Feature	Status	Notes
Package scope	MCP server implementation	❌	adk_mcp is client-only.
Transport	WebSocket/other non-HTTP non-stdio transports	❌	Only streamable HTTP and stdio are implemented.
Server request handling	Built-in business handlers for server-initiated requests	⚠️	Without onServerRequest, only ping is implicitly accepted.
Streaming lifecycle	Long-lived managed background subscription API	⚠️	readServerMessagesOnce() provides one SSE read pass; lifecycle orchestration is app-managed.
Auth	Built-in OAuth/token lifecycle manager	❌	Caller supplies headers/tokens; credential lifecycle is out of scope.
ADK integration	Runner/tool wiring for ADK agents	❌	Integration lives in adk_dart, not in adk_mcp.

Install

dart pub add adk_mcp

Usage

import 'package:adk_mcp/adk_mcp.dart';

final McpRemoteClient client = McpRemoteClient(
  clientInfoName: 'example_client',
  clientInfoVersion: '1.0.0',
);

final connection = StreamableHTTPConnectionParams(
  url: 'http://localhost:8000/mcp',
);

final Object? result = await client.call(
  connectionParams: connection,
  method: 'tools/list',
  params: const <String, Object?>{},
);

Repository

• https://github.com/adk-labs/adk_dart

License

Apache-2.0