The Model Context Protocol (MCP) underwent a significant revision on July 28, 2026, shifting to a stateless design and removing several key methods, including `initialize` and `ping`. This change has caused widespread issues for existing MCP servers and clients that were not updated to accommodate the new protocol. The errors, such as "Method not found: initialize" and "missing required request metadata," stem from the protocol's new requirement for requests to include session context via a `_meta` object with version and capability information. Server-initiated requests have been replaced by a multi-round-trip request (MRTR) mechanism where servers return early with an `input_required` status, prompting the client to resend the request with necessary input. AI
IMPACT Developers using the Model Context Protocol must update their servers and clients to comply with the new stateless design and request metadata requirements.
RANK_REASON Technical documentation detailing a protocol change and its impact on existing tools.
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