9 pages for additionalcontext.

Intercept and control agent behavior with hooks Claude Code CLI · in the page agent-sdk/hooks …fer-a-tool-call-for-later). * For `PostToolUse` hooks, you can set `additionalContext` to append information to the tool result. To replace the tool's output before Claude sees it, set `updatedToolO… Modifying system prompts Claude Code CLI · in the page agent-sdk/modifying-system-prompts …ctions in the next user message you send. * **From a hook**: return [`additionalContext`](/docs/en/hooks#add-context-for-claude) from a `UserPromptSubmit` or `PostToolUse` [hook callback](/docs/en/age… Agent SDK reference - Python Claude Code CLI · in the page agent-sdk/python …n: NotRequired[str] updatedInput: NotRequired[dict[str, Any]] additionalContext: NotRequired[str] class PostToolUseHookSpecificOutput(TypedDict): hookEventName: Literal["PostToolUse"]… Agent SDK reference - TypeScript Claude Code CLI · in the page agent-sdk/typescript …son?: string; updatedInput?: Record<string, unknown>; additionalContext?: string; } | { hookEventName: "UserPromptSubmit"; additionalContext?: string;… Explore the context window Claude Code CLI · in the page context-window …ettier after every file edit and reports back via `hookSpecificOutput.additionalContext`. That field enters Claude\'s context. Plain stdout on exit 0 does not. It is written to the debug log only.',… Hooks reference Claude Code CLI · in the page hooks …field the event supports is honored, including `permissionDecision`, `additionalContext`, `updatedInput`, and `systemMessage`, and the hook isn't reported as an error. * [Decision control](#decision… Automate actions with hooks Claude Code CLI · in the page hooks-guide …wer applies, in the order `deny`, `defer`, `ask`, `allow`. Text from `additionalContext` is kept from every hook and passed to Claude together. The example below registers two `PreToolUse` hooks on `… Monitoring Claude Code CLI · in the page monitoring-usage …v2.1.280 or later * `additional_context_chars`: Total characters of `additionalContext` returned by the matching hooks. Requires Claude Code v2.1.280 or later * `system_message_chars`: Total characte… Week 23 · June 1–5, 2026 Claude Code CLI · in the page whats-new/2026-w23 …">Stop and SubagentStop hooks</a> can return <code>hookSpecificOutput.additionalContext</code> to give Claude feedback and keep the turn going instead of being treated as an error</div> <div><code…