adk_mcp 2026.3.2+1

MCP protocol client primitives for ADK Dart packages.

adk_mcp

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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

Platform Support Matrix (Current)

Status legend:

• Y Supported
• Partial Partially supported / environment dependent
• N Not supported

Feature / Surface	Dart VM / CLI	Flutter (Android/iOS/Linux/macOS/Windows)	Flutter Web	Notes
McpRemoteClient (Streamable HTTP transport)	Y	Y	Y	HTTP/HTTPS only (StreamableHTTPConnectionParams).
Protocol negotiation + JSON-RPC helper methods	Y	Y	Y	Same protocol behavior across transports/platforms.
Server message/read loop (readServerMessagesOnce)	Y	Y	Y	Web requires CORS-compatible MCP endpoint for browser access.
McpStdioClient transport	Y	Partial	N	Web uses a stub that throws UnsupportedError; non-web requires local process support.
StdioConnectionParams process spawn (Process.start)	Y	Partial	N	Environment-dependent on Flutter runtime/sandbox policies.
HTTP session termination (terminateSession)	Y	Y	Y	Uses MCP Streamable HTTP DELETE termination flow.
Built-in credential/token lifecycle manager	N	N	N	Headers/tokens are caller-managed.

Feature Support Matrix (Current)

Status legend:

• Y Supported
• Partial Partial / integration required
• N Not supported yet

Supported / Working

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

Partial / Not Yet Supported

Area	Feature	Status	Notes
Package scope	MCP server implementation	N	adk_mcp is client-only.
Transport	WebSocket/other non-HTTP non-stdio transports	N	Only streamable HTTP and stdio are implemented.
Server request handling	Built-in business handlers for server-initiated requests	Partial	Without onServerRequest, only ping is implicitly accepted.
Streaming lifecycle	Long-lived managed background subscription API	Partial	readServerMessagesOnce() provides one SSE read pass; lifecycle orchestration is app-managed.
Auth	Built-in OAuth/token lifecycle manager	N	Caller supplies headers/tokens; credential lifecycle is out of scope.
ADK integration	Runner/tool wiring for ADK agents	N	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