vercel/ai @ai-sdk/mcp@2.0.0

on GitHub

Major Changes

• 23fa161: fix(mcp): setting redirect: error for MCP transport
• ef992f8: Remove CommonJS exports from all packages. All packages are now ESM-only ("type": "module"). Consumers using require() must switch to ESM import syntax.
• 8359612: Start v7 pre-release

Patch Changes

• b79094c: Add resource_link content type to CallToolResultSchema and PromptMessageSchema per MCP spec. Fixes hard rejection when MCP servers return resource_link content parts with zod ≥ 4.4.x.

• 78e0023: fix(mcp): await addClientAuthentication in token exchange and refresh

• b567a6c: dependency updates

• e33ad0b: fix(mcp): add optional hook to validate authorization servers

• e3ea484: fix(mcp): bypass outputSchema validation when tool returns isError

• 93afb28: feat(mcp): expose server instructions to be accessible through client

• a00d1d3: feat(mcp): allow custom fetch for HTTP and SSE transports

• a98bf66: feat(mcp): surface 'serverInfo' exposed from the MCP server

• 2a150f8: fix(mcp): lock first sse endpoint received via event

• 2655da8: fix(mcp): use negotiated protocol version in transport request headers

• 9f0e36c: trigger release for all packages after provenance setup

• f7bc0b4: feat(mcp): expose statusCode, url, and responseBody on MCPClientError for HTTP transport failures

  MCPClientError now carries structured HTTP context when it originates from the
  streamable HTTP transport. This lets downstream consumers (e.g. agent frameworks
  that need to decide whether to fall back from streamable HTTP to legacy SSE
  transport per the MCP spec) branch on the actual response status without parsing
  the error message string.

  Fields are optional — they remain undefined for stdio transport errors and for
  non-response failures (network errors, aborts).

• dcefad3: fix(mcp): respond to ping requests with an empty result per JSON-RPC spec (closes #6282)

• b44b051: fix(mcp): prevent prototype-named tools from bypassing the schemas allowlist

  When using client.tools({ schemas }) to expose only an explicitly allowed
  subset of an MCP server's tools, the allowlist check used the in operator,
  which also matches inherited Object.prototype properties. A server-advertised
  tool named constructor, toString, __proto__, etc. would pass the check
  even though the developer never defined it in schemas, and was then exposed to
  the model and executable. The check now uses Object.hasOwn, so only
  explicitly defined tools are returned.

• f634bac: feat(mcp): add new McpProviderMetadata type

• b9b3899: changeset for #13384

• 1e89d62: fix(mcp): strip trailing slash from OAuth resource parameter

• 3e0b82f: fix(mcp): support official sdk protocol version negotiation

• 1451759: feat(mcp): deprecate name and use clientName for MCPClient

• 7fc6bd6: Raise minimum supported Node.js version to 22. Supported versions: 22, 24, and 26.

• 08d2129: feat(mcp): propagate the server name through dynamic tool parts

• 58c9eb1: feat(mcp): add redirect option to MCPTransportConfig for controlling HTTP redirect behavior

• 0c4c275: trigger initial canary release

• 611f621: feat(mcp): feat(mcp): add support for MCP Apps

• 9ecd8ae: fix(mcp): add MCP protocol version 2025-11-25 to supported versions

• 6c17a9f: fix(mcp): deduplicate auth refresh on http transport

• 69254e0: feat(ai): add toolMetadata for tool specific metdata

• 258c093: chore: ensure consistent import handling and avoid import duplicates or cycles

• f0c6770: fix(mcp): prevent mcp oauth credential exfiltration during rediscovery

• 5463d0d: feat(provider): align tool result output content file part types with top-level message file part types

• b8396f0: trigger initial beta release

• b29e087: fix (mcp): handle SSE messages without explicit event fields

• 90e2d8a: chore: fix unused vars not being flagged by our lint tooling

• 024a6b4: fix(mcp): validate oauth metadata issuer during discovery

• 9b0bc8a: fix(mcp): prevent prototype pollution by using secureJsonParse

• ff5eba1: feat: roll image-* tool output types into their equivalent file-* types