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Sweep 22 Sep 2026 · 17:19Z Build v2.1.280 501 read Stable v2.1.267 Latest v2.1.280 Next v2.1.280 Feeds RSS JSON llms.txt Unofficial
Claude Code v2.1.259 ·

Headless SDK sessions expose a bindable $.tool.register API for MCP servers

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Headless SDK sessions expose a session object for MCP servers with addMcpServer, removeMcpServer, toast, status and refreshContext.

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AreaSDKwhat it touches
KindNew Featuresin v2.1.259,
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Headless SDK sessions expose a session object for MCP servers with addMcpServer, removeMcpServer, toast, status and refreshContext.

Headless SDK sessions now expose a $.tool.register-style session object with addMcpServer, removeMcpServer, toast, status, and refreshContext hooks for MCP servers. In a headless session, calls to toast and status are logged rather than displayed, since there is no notification bar or status row to show them in.

Read from
Names in the bundleaddMcpServerremoveMcpServerrefreshContext
What the documentation says
Documented inapi/agents-and-tools/mcp-connector
Since it was published

The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.

Confirmed since Anthropic's documentation has since written up addMcpServer, on permission-policies. .addMcpServer( managed-agents/permission-policies see the edit
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agreesAnthropic's documentation has since written up addMcpServer, on permission-policies.

See this entry in the whole of v2.1.259 →

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