Some MCP servers' resources can no longer be read from subagents or background sessions
Claude Code now refuses to read resources from certain MCP servers inside a subagent or background session and tells the model to use that server's tools
You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
MCPArea: what it touches
ImprovementsKind: in v2.1.323,
ImprovementsSection of the release
Unclear Which MCP servers this refusal applies to is not stated.
What
MCP servers are outside programs that give Claude Code extra tools and data. The data they offer for reading is called resources. A subagent is a helper that Claude starts to work on part of a task, and a background session is one that runs without a terminal window attached.
For certain MCP servers, Claude Code now refuses to read their resources from a subagent or a background session. The refusal explains that the server would treat the request as if it came from the main session. The model is told to use that server's tools instead, if it has them. Before this, only the account memory server was held back this way.
Why
Some resource reads that used to work inside subagents or background sessions will now be refused. If a subagent seems unable to read a server's data, this may be the reason.
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 doubtWhich MCP servers this refusal applies to is not stated.
