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

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`.

ADK 2.0 Compatibility

This package is fully aligned with ADK 2.0, supporting remote MCP server integration, Managed Agent configurations, and GCP Managed Agents Interactions API for hybrid agent execution.

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