{"name":"SendMessage","slug":"sendmessage","family":"tool","title":"Tools","noun":"tool","description":"Messages arriving from another session now show who sent them plus a chord to expand.","description_source":"entry","described_by":{"version":"2.1.222","anchor":"messages-from-other-sessions-get-a-sanitized-sender-label"},"presence":{"first_seen":"2.1.186","removed_in":null,"in_current_build":true,"newest_mined":"2.1.308","builds":107,"mined_builds":149,"first_cited":{"version":"2.1.178","released_at":"2026-06-15 19:03:37","spans":8}},"aliases":[],"entries":[{"version":"2.1.304","anchor":"shutdown-approval-refused-outside-a-teammate-session","heading":"Only a teammate can approve a shutdown request now","line":"SendMessage now refuses a shutdown approval from a session that is not a teammate, and says to send a shutdown request instead","released_at":"2026-10-19 19:47:15","reason":"found in this entry's text"},{"version":"2.1.304","anchor":"sendmessage-held-when-delivery-is-not-reachable","heading":"Messages to teammates can now be refused before delivery","line":"SendMessage now runs a check before delivering, and when the check fails it reports that the teammate or main conversation was not messaged","released_at":"2026-10-19 19:47:15","reason":"found in this entry's text"},{"version":"2.1.301","anchor":"subagent-sendresume-budget-between-user-messages","heading":"Limit on how often agents can be messaged or resumed between your messages","line":"Messaging or resuming a subagent now counts against a limit that resets when you write, and is refused with a 'Not sent' message once used up","released_at":"2026-10-15 14:34:23","reason":"found in this entry's text"},{"version":"2.1.299","anchor":"send-message-via-an-mcp-bridge-tool-behind-tengu-flickering","heading":"SendMessage can look up an MCP server's send_message tool for bridged messages","line":"When sending to a bridge address, Claude Code can now find a connected MCP server's send_message tool, behind a switch that is off by default","released_at":"2026-10-14 00:23:19","reason":"found in this entry's text, named in this entry"},{"version":"2.1.299","anchor":"stopped-agents-refused-for-resume-via-sendmessage-live-agen","heading":"Messages to stopped agents are refused, and queued replies say to wait","line":"Messaging an agent you stopped now returns a clear refusal, and a queued message tells Claude to wait instead of resending","released_at":"2026-10-14 00:23:19","reason":"found in this entry's text, named in this entry"},{"version":"2.1.299","anchor":"subagent-report-delivery-and-send-message-errors","heading":"Subagents must send their final report with a dedicated call","line":"Agents are now told that a final report written as plain text is not delivered, and `SendMessage` gains new refusal messages","released_at":"2026-10-14 00:23:19","reason":"found in this entry's text"},{"version":"2.1.296","anchor":"sendmessage-prompt-drops-inboxteammate-wording-in-a-new-mod","heading":"SendMessage tool has alternative wording that limits messages to this session","line":"In one mode, the SendMessage tool's instructions now say Claude can message only agents of this session and that no one outside it can be reached","released_at":"2026-10-09 16:58:10","reason":"found in this entry's text"},{"version":"2.1.296","anchor":"cross-session-messaging-own-agents-only-refusal","heading":"SendMessage can refuse a message as limited to the session's own agents","line":"SendMessage can now refuse to deliver a message early, reporting that messaging is limited to the session's own agents","released_at":"2026-10-09 16:58:10","reason":"found in this entry's text"},{"version":"2.1.296","anchor":"sendmessage-to-field-gets-a-description-agent-tool-gets-c","heading":"SendMessage explains who a message can go to","line":"The recipient field of `SendMessage` now explains its allowed values, and the `Agent` tool gains a step that adjusts its input","released_at":"2026-10-09 16:58:10","reason":"found in this entry's text"},{"version":"2.1.296","anchor":"sendmessage-restricted-to-own-agents-in-some-mode-teammate","heading":"SendMessage can now refuse some message targets","line":"A new check on who a SendMessage is addressed to can block the send, and one error message has a shorter form","released_at":"2026-10-09 16:58:10","reason":"found in this entry's text"}],"entries_total":62,"docs":[{"source":"api","path":"manage-claude\/opentelemetry\/api","title":"api","documented":false},{"source":"claude-code","path":"agent-sdk\/subagents","title":"Subagents in the SDK","documented":false},{"source":"claude-code","path":"agent-sdk\/typescript","title":"Agent SDK reference - TypeScript","documented":false},{"source":"claude-code","path":"agent-teams","title":"Orchestrate teams of Claude Code sessions","documented":false},{"source":"claude-code","path":"changelog","title":"Claude Code changelog","documented":false},{"source":"claude-code","path":"cross-session-messaging","title":"Message your other Claude Code sessions","documented":false},{"source":"claude-code","path":"permission-modes","title":"Choose a permission mode","documented":false},{"source":"claude-code","path":"plugins\/mods\/api","title":"Use the mods API","documented":false},{"source":"claude-code","path":"plugins\/mods\/reference","title":"Mods reference","documented":false},{"source":"claude-code","path":"settings","title":"Claude Code settings","documented":false}],"docs_total":12,"gates":[],"related":[],"url":"https:\/\/changelogs.core-directive.com\/reference\/tool\/sendmessage","family_url":"https:\/\/changelogs.core-directive.com\/reference\/tool.json"}