What probably matters to youSection of the release
What
claude mcp serve runs Claude Code as an MCP server, so other programs can use its tools. A subagent is a helper Claude starts for a separate task.
mcp serve now loads your agent definitions before it lists tools or answers calls. The Agent tool description includes an Available agent types: list, and subagent calls use those definitions. Before, the lists were empty.
The internal restrictions gain backgroundAgentLaunchDisabled and remoteAgentIsolationDisabled, set by disableBackgroundAgentLaunch() and disableRemoteAgentIsolation(). Before, only background tasks, unsandboxed commands and a deadline could be disabled this way.
In the restricted (http) mode of mcp serve, background-agent launch and remote-agent isolation are both turned off.
Why
Programs connected through claude mcp serve can now see and use your custom subagents. Background agents can be blocked without switching off every background task.
Read from
Names in the bundleclaude mcp serve
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtIt is not clear exactly which connection types count as the restricted HTTP mode.
