ai_sdk_mcp 2.0.0

MCP (Model Context Protocol) client for AI SDK Dart. Connect to MCP servers via Streamable HTTP or stdio, discover tools, and use them with any LLM provider.

2.0.0

• Hardened Streamable HTTP reconnection, session cleanup, cancellation notifications, response trust boundaries, and concurrent shutdown.
• Removed stdio lifecycle races and prevented cleanup from suppressing unexpected MCP client errors.
• Stdio JSON frames are capped at 1 MiB and terminate safely on overflow.

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1.2.0

Breaking

• Removed the legacy HTTP transport exports SseClientTransport and HttpClientTransport. Use StreamableHttpClientTransport for remote MCP servers.
• The HTTP client now negotiates and enforces MCP protocol 2025-06-18. Deprecated HTTP+SSE servers that only speak 2024-11-05 are no longer a supported target.

Transport behavior

• StreamableHttpClientTransport speaks the Streamable HTTP transport against a single MCP endpoint.
• Each client message is sent as an HTTP POST, and the server may answer with either JSON or SSE for that request.
• After initialize succeeds, the client sends notifications/initialized, reuses MCP-Protocol-Version on later HTTP requests, and starts the optional GET SSE listener for server-pushed notifications.
• If the server returns Mcp-Session-Id, the transport reuses it on later POST / GET / DELETE requests, reconnects the optional listener with Last-Event-ID after disconnects, and sends DELETE on close().
• Request timeouts send a best-effort notifications/cancelled notification before the call fails locally.
• Custom headers and an injected http.Client are supported. Injected clients remain caller-owned; the transport closes only the client it creates.

Web / native

• Flutter-web compatible. The package no longer imports dart:io at the top level. StdioMCPTransport (which spawns a process) now lives behind a conditional import: the real dart:io implementation is used on native platforms, and a stub that throws UnsupportedError is used on web.
• MCPTransport exposes a notifications stream for server-initiated messages. notifications/resources/updated continue to drive subscribeResource() listeners automatically.

Migration

Replace remote transport construction like this:

final transport = StreamableHttpClientTransport(
  url: Uri.parse('https://mcp.example.com/mcp'),
  headers: {'Authorization': 'Bearer <token>'},
);

Notes:

• Point the transport at the MCP endpoint itself, not a legacy /sse endpoint.
• Keep required credential headers in headers, but avoid embedding long-lived secrets inside distributed browser or mobile clients.
• If you need a shared http.Client, inject it and close it yourself after the MCP client shuts down.

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1.1.0

• Bumped ai_sdk_dart constraint to ^1.1.0.
• No MCP client behaviour changes; version aligned with the rest of the monorepo.

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1.0.0+1

• Improved pubspec descriptions for better pub.dev discoverability.
• Added example/example.md with usage examples and links to runnable apps.

1.0.0

First stable release. Depends on ai_sdk_dart 1.0.0.

• MCPClient — manages a session with any MCP server via pluggable transport.
• SseClientTransport — HTTP SSE transport for remote MCP servers; supports custom headers and separate POST URL.
• StdioMCPTransport — stdio transport that spawns a local process and communicates via stdin/stdout.
• initialize() — MCP protocol 2024-11-05 handshake with idempotency guard.
• tools() — discovers available tools and returns a ToolSet compatible with generateText / streamText.
• callTool() — invokes a named tool with structured arguments; throws MCPException on server-side errors.
• MCPException — typed exception with message field.

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0.2.0

• Initial release.
• MCPClient — manages a connection to an MCP server via any transport.
• SseClientTransport — HTTP SSE transport for remote MCP servers.
• StdioMCPTransport — stdio transport for local MCP server processes.
• tools() — discovers available tools and returns a typed ToolSet.
• callTool() — invokes a named tool with structured arguments.
• MCP protocol 2024-11-05 initialize handshake.
• MCPException for server-side errors.