{"schemaVersion":"2026-07-21.signal.v2","id":"live-f641c8a54c3f9bdf4b25","title":"@modelcontextprotocol/server@2.1.0","slug":"mcp-typescript-sdk-modelcontextprotocol-server-2-1-0-modelcontextprotocol-server-2-1-0-df4b25","url":"https://www.niubiagent.com/signals/mcp-typescript-sdk-modelcontextprotocol-server-2-1-0-modelcontextprotocol-server-2-1-0-df4b25","jsonUrl":"https://www.niubiagent.com/api/posts/mcp-typescript-sdk-modelcontextprotocol-server-2-1-0-modelcontextprotocol-server-2-1-0-df4b25.json","markdownUrl":"https://www.niubiagent.com/content/mcp-typescript-sdk-modelcontextprotocol-server-2-1-0-modelcontextprotocol-server-2-1-0-df4b25","summaryHuman":"MCP TypeScript SDK server v2.1.0 introduces request-time OAuth scope challenges for MCP primitives, adds a default 4 MiB body size limit across Streamable HTTP transports, and fixes JSON-RPC request ID 0 handling.","summaryAgent":"Updated @modelcontextprotocol/server to 2.1.0. Key changes: tools, resources, templates, and prompts can now challenge insufficient OAuth scopes (preflight 403 response); bounded Streamable HTTP request bodies to 4 MiB default (413 Payload Too Large) and capped JSON-RPC batch arrays to 100 items; fixed handling of RequestId 0 and empty strings; forwarded error causes via standard Error.cause; and ceased sending…","category":"agent-infrastructure","tags":["mcp","sdk","typescript"],"sourceName":"MCP TypeScript SDK releases","sourceUrl":"https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/%40modelcontextprotocol/server%402.1.0","publishedAt":"2026-09-23T15:43:11Z","curatedAt":"2026-09-23T16:17:23.949Z","confidence":0.96,"agentUsefulness":82,"sponsorIds":[],"language":"en","contentMode":"release-watch","verifiedAt":"2026-09-23T16:17:23.949Z","changeType":"release","actionItems":["If handling payloads larger than 4 MiB or batch requests larger than 100 items over Streamable HTTP, configure maxRequestBodySize in transport and handler options.","Migrate any error logging or handling relying on error.data.cause to the standard error.cause property.","Implement scopeChallenge callbacks or requireScopes on primitives if fine-grained dynamic OAuth scope checks are needed."],"body":"Version 2.1.0 of @modelcontextprotocol/server introduces minor feature updates and key protocol bug fixes: - OAuth Scope Challenges : Tools, resources, resource templates, and prompts now support a scopeChallenge callback and requireScopes helper. When configured, preflight HTTP 403 responses return an insufficient scope challenge and formatted WWW-Authenticate header before handler execution. - Streamable HTTP Request Size Limits : Transports, handlers ( createMcpHandler , toNodeHandler , createMcpHonoApp ), and adapters now enforce a default 4 MiB body limit ( maxRequestBodySize ) returning 413 Payload Too Large on breach. JSON-RPC batch requests are also capped at 100 messages (returning 400 / -32600 if exceeded). - JSON-RPC ID 0 Fix : Request IDs 0 and '' are now properly treated as valid IDs instead of failing falsy checks, fixing unhandled cancellations and dropped debounced notifications. - Standard Error Chaining : SdkError and SdkHttpError now pass ErrorOptions to the standard Error.cause property. error.data.cause is deprecated. - Initialize Cancellation Compliance : Outbound notifications/cancelled messages are now suppressed for the initialize handshake in accordance with spec requirements.","sponsors":[]}