Support Anthropic's Native MCP Connector API (mcp_servers parameter)

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Description

Anthropic recently released an MCP Connector feature that allows Claude's Messages API to connect directly to remote MCP servers via the mcp_servers parameter (requires anthropic-beta: mcp-client-2025-04-04 header).

Adding support for Anthropic's native connector would enable:

• Direct MCP server connections via Claude's Messages API
• OAuth bearer token authentication for MCP servers
• Multiple simultaneous MCP server connections
• Tool access without local MCP client implementation

Reference: https://docs.claude.com/en/docs/agents-and-tools/mcp-connector

AI SDK Version

"ai": "^5.0.59",
"@ai-sdk/anthropic": "^2.0.22",

Code of Conduct

• I agree to follow this project's Code of Conduct

[lgrammel]

Identify issue type

Identified as Feature
Confidence: High

Rationale

This is a request to add support for a new Anthropic provider API capability, so it is a feature rather than a bug.

Evidence

• The issue requests support for Anthropic's mcp_servers parameter and required beta header.
• It proposes new capabilities including direct remote MCP connections, OAuth bearer authentication, and multiple simultaneous MCP servers.
• No existing documented AI SDK behavior is reported as broken.