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Sweep 12 Nov 2026 · 23:00Z Build v2.1.323 540 read Stable v2.1.311 Latest v2.1.323 Next v2.1.323 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.323 ·

Remote sessions send extra tool-container headers on MCP requests

In remote sessions, MCP requests now carry extra headers about tool containers in some cases

Under the hood Internal Changes
JSON All of v2.1.323
Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
SessionsArea: what it touches
Internal ChangesKind: in v2.1.323,
Internal ChangesSection of the release

Unclear It is not clear what makes the asked-for headers be sent in a session.

What

MCP is the protocol Claude Code uses to talk to external tool servers. In remote sessions (ones running on Anthropic's servers), outgoing MCP requests previously carried only a tool-use ID header. They can now also carry:

  • x-ccr-tool-container-call-owed: sent on tool calls when an owed state is active.
  • X-Ccr-Tool-Container-Asked-For and X-Ccr-Tool-Container-Asked-For-Basis: sent on non-GET requests when a provider for them is registered.

Ping requests are recognized and handled separately.

Why

This is a change in what remote sessions tell the server, not something set by users.

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 what makes the asked-for headers be sent in a session.

See this entry in the whole of v2.1.323 →

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