Atlassian MCP plugin: migrate from deprecated HTTP+SSE to Streamable HTTP before June 30 2026

Summary

The official Atlassian MCP plugin (atlassian@claude-plugins-official) currently connects via the HTTP+SSE transport endpoint at https://mcp.atlassian.com/v1/sse. Atlassian has announced this endpoint will be removed after June 30, 2026 in favor of the Streamable HTTP transport at https://mcp.atlassian.com/v1/mcp.

Users of the managed plugin have no way to change the transport URL themselves — the plugin handles the connection internally. This means the migration needs to happen in the plugin/Claude Code integration before the cutoff date.

Deprecation Notice

Atlassian is injecting this warning into every MCP tool response:

After 30th June 2026, usage of the HTTP+SSE transport endpoint at https://mcp.atlassian.com/v1/sse will no longer be supported. Recommend clients to point to the Streamable HTTP transport endpoint at https://mcp.atlassian.com/v1/mcp.

Atlassian's official deprecation notice: https://community.atlassian.com/forums/Atlassian-Remote-MCP-Server/HTTP-SSE-Deprecation-Notice/ba-p/3205484

Why the Change

Per Atlassian:

• HTTP+SSE is fragile during network drops; SSE sessions are harder to recover cleanly
• The MCP specification prioritizes Streamable HTTP as the standard transport method

What Needs to Happen

Update the Atlassian managed plugin to connect to https://mcp.atlassian.com/v1/mcp instead of https://mcp.atlassian.com/v1/sse, using the http-first transport mode.

Impact

All Claude Code users with the Atlassian plugin enabled (atlassian@claude-plugins-official) will lose Jira/Confluence MCP access after June 30, 2026 if the plugin is not updated.