What's Changed

• Improve NetworkTransport and add test coverage by @mattt in #108
• Prevent double continuation resumption in client by @mattt in #113
• Add test coverage for base64 data helper methods by @mattt in #114
• Add support for sampling by @mattt in #119
• Improve ergonomics of prompt and sampling message initialization by @mattt in #120
• Update Client.connect(transport:) to automatically send initialize request by @mattt in #100

Full Changelog: 0.8.2...0.9.0

What's Changed

• Implement client protocol version negotiation in server initialization by @mattt in #107

Full Changelog: 0.8.1...0.8.2

What's Changed

• Don't throw error if there's a protocol mismatch between client and server by @mattt in #103

Full Changelog: 0.8.0...0.8.1

What's Changed

• Update Client.listTools return type to include next cursor by @mattt in #54
• Add support for Linux with glibc by @mattt in #61
• Conditionalize availability of StdioTransport by @mattt in #65
• Fix testServerHandleInitialize flake by @mattt in #68
• Add support for JSON-RPC batching by @mattt in #67
• Add support for audio content in prompts and tool results by @mattt in #73
• Add support for tool annotations by @mattt in #47
• Add streamable HTTP transport for clients by @mattt in #70
• Update README with information about transports and platform availability by @mattt in #76
• Simplify receive() implementation for transports by @mattt in #78
• Send initialized notification from client instead of server by @mattt in #85
• Update AnyNotification to include notification params by @stallent in #86
• Fix event stream line parsing to handle CRLF and empty lines correctly by @aspitz in #89
• support 405 response from servers that don’t support streaming by @stallent in #90
• Document Client usage with HTTPClientTransport by @mattt in #77
• Resume NetworkTransfer with EOF instead of throwing error when no data is received by @mattt in #94
• Use EventSource for SSE implementation by @stallent and @mattt in #96
• Delay SSE GET connection until after session ID is established by @mattt in #97
• Improve documentation comments for transport types by @mattt in #98
• Expand README with more information about client and server usage by @mattt in #99
• Set latest version to 2025-03-26 by @mattt in #80

New Contributors

• @stallent made their first contribution in #86
• @aspitz made their first contribution in #89

Full Changelog: 0.7.1...0.8.0

What's Changed

• Remove top-level MCP enumeration by @mattt in #53

Full Changelog: 0.7.0...0.7.1

Breaking Changes

Error renamed to MCPError

Renamed the Error type to MCPError to avoid namespace collision with Swift's standard Error protocol. The MCPError type now properly conforms to Swift.Error.

// Old code
catch let error as MCP.Error {
    // Handle MCP error
}
// New code
catch let error as MCPError {
    // Handle MCP error
}

Transport protocol updated to use Data instead of String

The Transport protocol methods now work with Data instead of String to avoid unnecessary memory copies:

// Old protocol signature
func send(_ message: String) async throws
func receive() async throws -> String
// New protocol signature
func send(_ data: Data) async throws
func receive() async throws -> Data

This change should not affect most users who rely on the standard StdioTransport, but will require updates if you've implemented a custom transport.

What's Changed

• Update README to reflect MIT License by @mattt in #41
• Add configurable strict mode for MCP client initialization by @mattt in #43
• Update transports to send and receive data instead of strings by @mattt in #42
• Rename Error to MCPError by @mattt in #44
• Add Changelog section to README by @mattt in #45

Full Changelog: 0.6.0...0.7.0

What's Changed

• Set permissions for CI workflow by @mattt in #29
• Transfer project to @modelcontextprotocol by @mattt in #28
• Add waitUntilComplete() method to Server by @adamwulf in #26
• Import System package when available by @mattt in #34
• Fix/decode tool call by @adamwulf in #36
• Update platform requirements by @mattt in #30

Full Changelog: 0.5.1...0.6.0

What's Changed

• Add unit test to check that AnyRequest handles missing parameters by @adamwulf in #24

New Contributors

• @adamwulf made their first contribution in #24

Full Changelog: 0.5.0...0.5.1

What's Changed

• Configure JSON encoding format options by @mattt in #21
• Add server initialization hook by @mattt in #19
• Ensure Request decoder handles missing/null params correctly by @mattt in #22

Full Changelog: 0.4.2...0.5.0

What's Changed

• Revert "Update capabilities to be expressible by Boolean literals" by @mattt in #18

Full Changelog: 0.4.1...0.4.2