Fetching from the wire…
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Public story · 2026-07-31 · high
A dropped connection now loses the in-flight tool call instead of resuming it, per the July 28 changelog.
Why now: SEP-2575 posted to the MCP changelog on July 28, and this covers it as of July 31.
MCP's latest spec update strips stream resumability from Streamable HTTP, per SEP-2575's July 28 changelog. That's a real risk for anyone running tool calls over flaky networks: the work just vanishes instead of picking back up.
The protocol used to reconnect a broken SSE stream with the Last-Event-ID header, replaying whatever messages the client missed. SEP-2575 removes that machinery, per the changelog.
Long-running work moves instead to the io.modelcontextprotocol/tasks extension. A server can hand back a task handle without being asked, and the client polls it with tasks/get until the job finishes. A new tasks/update method lets the client push more input into a task that's still running, something the old resumable-stream model never supported.
The changelog doesn't say what happens to clients still coded for the old reconnect behavior. A call that assumed the transport would resume it now needs its own retry logic, or it times out and the work is lost.
Each link below shares sources, entities, or timing with this story.
MCP deprecates Roots / Shared entities / Same source / Shared topic / Earlier coverage
Linked by a graph relationship (MCP deprecates Roots); both cover MCP, Streamable HTTP; cite the same source (SEP-2575).
MCP deprecates Roots / Shared entities / Shared topic / Earlier coverage
Linked by a graph relationship (MCP deprecates Roots); both cover MCP, SEP, SSE; overlapping topics (call, task).
OpenAI supports MCP / Shared entities / Earlier coverage / Tension
Linked by a graph relationship (OpenAI supports MCP); both cover IDs, MCP; earlier IDs coverage from 2026-07-23.
MCP deprecates Roots / Shared entity: MCP / Shared topic / Earlier coverage
Linked by a graph relationship (MCP deprecates Roots); both cover MCP; overlapping topics (call, extension, task).
MCP supports OpenID Connect / Shared entity: MCP / Shared topic / Earlier coverage
Linked by a graph relationship (MCP supports OpenID Connect); both cover MCP; overlapping topics (call, extension, header).
Unreal Engine supports MCP / Shared entities / Earlier coverage
Linked by a graph relationship (Unreal Engine supports MCP); both cover Any MCP, MCP; earlier Any MCP coverage from 2026-06-19.
Anthropic released MCP / Shared entities / Earlier coverage
Linked by a graph relationship (Anthropic released MCP); both cover IDs, MCP; earlier IDs coverage from 2026-06-16.
Linked by a graph relationship (Anthropic released MCP); both cover Any MCP, MCP; earlier Any MCP coverage from 2026-03-07.