ui: move get_datetime tool to frontend (#27255)

* ui: move get_datetime tool to frontend

* clarify docs

* server: drop the now unused ctime include

strftime() and gmtime_r() were the only users, both went away with the
get_datetime tool. Also make the renderer's catch inert: the browser
executor always emits JSON, so a non-JSON result is no longer a date to
display.

---------

Co-authored-by: Pascal <admin@serveurperso.com>

common/arg.cpp

@@ -3362,7 +3362,7 @@ common_params_context common_params_parser_init(common_params & params, llama_ex
         {"--tools"}, "TOOL1,TOOL2,...",
         "experimental: whether to enable built-in tools for AI agents - do not enable in untrusted environments (default: no tools)\n"
         "specify \"all\" to enable all tools\n"
-        "available tools: read_file, file_glob_search, grep_search, exec_shell_command, write_file, edit_file, get_datetime, get_info\n"
+        "available tools: read_file, file_glob_search, grep_search, exec_shell_command, write_file, edit_file, get_info\n"
         "note: for security reasons, this will limit --cors-origins to localhost by default",
         [](common_params & params, const std::string & value) {
             params.server_tools = parse_csv_row(value);

tools/server/README.md

@@ -196,7 +196,7 @@ For the full list of features, please refer to [server's changelog](https://gith
 | `--ui-config, --webui-config JSON` | JSON that provides default UI settings (overrides UI defaults)<br/>(env: LLAMA_ARG_UI_CONFIG) |
 | `--ui-config-file, --webui-config-file PATH` | JSON file that provides default UI settings (overrides UI defaults)<br/>(env: LLAMA_ARG_UI_CONFIG_FILE) |
 | `--ui-mcp-proxy, --webui-mcp-proxy, --no-ui-mcp-proxy, --no-webui-mcp-proxy` | experimental: whether to enable MCP CORS proxy - do not enable in untrusted environments (default: disabled)<br/>(env: LLAMA_ARG_UI_MCP_PROXY) |
-| `--tools TOOL1,TOOL2,...` | experimental: whether to enable built-in tools for AI agents - do not enable in untrusted environments (default: no tools)<br/>specify "all" to enable all tools<br/>available tools: read_file, file_glob_search, grep_search, exec_shell_command, write_file, edit_file, get_datetime, get_info<br/>note: for security reasons, this will limit --cors-origins to localhost by default<br/>(env: LLAMA_ARG_TOOLS) |
+| `--tools TOOL1,TOOL2,...` | experimental: whether to enable built-in tools for AI agents - do not enable in untrusted environments (default: no tools)<br/>specify "all" to enable all tools<br/>available tools: read_file, file_glob_search, grep_search, exec_shell_command, write_file, edit_file, get_info<br/>note: for security reasons, this will limit --cors-origins to localhost by default<br/>(env: LLAMA_ARG_TOOLS) |
 | `--tools-runtime OPTION` | experimental: run tools in a separate runtime environment (default: none, use host environment)<br/>available options:<br/>  'docker:<image>', 'podman:<image>': spin up a new container and reuse it for all invocations, clean up on server exit<br/>  'docker-container:<id>', 'podman-container:<id>': use an existing container by ID, won't stop on server exit<br/>  'ssh:<target>': run tools on a remote POSIX host over SSH, key-based auth and a trusted host key are required<br/><br/>(env: LLAMA_ARG_TOOLS_RUNTIME) |
 | `--mcp-servers-config PATH` | experimental: path to JSON file with MCP server definitions (Cursor-compatible format) - do not enable in untrusted environments (default: none)<br/>note: for security reasons, this will limit --cors-origins to localhost by default<br/>(env: LLAMA_ARG_MCP_SERVERS_CONFIG) |
 | `--mcp-servers-json JSON` | experimental: inline JSON with MCP server definitions (Cursor-compatible format) - do not enable in untrusted environments (default: none)<br/>note: for security reasons, this will limit --cors-origins to localhost by default<br/>(env: LLAMA_ARG_MCP_SERVERS_JSON) |

tools/server/server-tools.cpp

@@ -8,7 +8,6 @@
 #include <regex>
 #include <thread>
 #include <chrono>
-#include <ctime>
 #include <atomic>
 #include <cstring>
 #include <cctype>
@@ -1692,61 +1691,6 @@ private:
     }
 };
 
-//
-// get_datetime: returns the current date and time
-//
-
-struct server_tool_get_datetime : server_tool {
-    server_tool_get_datetime() {
-        name = "get_datetime";
-        display_name = "Get Date & Time";
-        permission_write = false;
-    }
-
-    json get_definition() const override {
-        return {
-            {"type", "function"},
-            {"function", {
-                {"name", name},
-                {"description", "Returns the current date and time in UTC"},
-                {"parameters", {
-                    {"type", "object"},
-                    {"properties", {
-                        {"format", {
-                            {"type", "string"},
-                            {"description",
-                                "strftime()-style format string for the output (default: \"%Y-%m-%dT%H:%M:%SZ\", "
-                                "e.g. ISO 8601). Choose your own format if you need something else, "
-                                "e.g. \"%A, %B %d %Y\" for a human-readable date."},
-                        }},
-                    }},
-                }},
-            }},
-        };
-    }
-
-    json invoke(json params, server_tool::stream *) const override {
-        std::string format = json_value(params, "format", std::string("%Y-%m-%dT%H:%M:%SZ"));
-
-        auto now  = std::chrono::system_clock::now();
-        auto time = std::chrono::system_clock::to_time_t(now);
-        std::tm tm_utc;
-#ifdef _WIN32
-        gmtime_s(&tm_utc, &time);
-#else
-        gmtime_r(&time, &tm_utc);
-#endif
-
-        char buf[256];
-        size_t len = std::strftime(buf, sizeof(buf), format.c_str(), &tm_utc);
-        if (len == 0) {
-            return {{"error", "invalid format string"}};
-        }
-
-        return {{"result", std::string(buf, len)}};
-    }
-};
-
 //
 // get_info: returns runtime info (OS name/version and cwd)
 //
@@ -2005,6 +1949,10 @@ static server_tool & find_tool(std::vector<std::unique_ptr<server_tool>> & tools
 //
 
 static std::vector<std::unique_ptr<server_tool>> build_tools() {
+    // IMPORTANT: for contributors, please keep this array of tools as minimal as possible
+    //            we only accept minimal i/o and shell command tools here
+    //            for example, do not add: web search, get date time, etc.
+    //            high-level functionality should be added either via MCP or web UI
     std::vector<std::unique_ptr<server_tool>> tools;
     tools.push_back(std::make_unique<server_tool_read_file>());
     tools.push_back(std::make_unique<server_tool_file_glob_search>());
@@ -2012,7 +1960,6 @@ static std::vector<std::unique_ptr<server_tool>> build_tools() {
     tools.push_back(std::make_unique<server_tool_exec_shell_command>());
     tools.push_back(std::make_unique<server_tool_write_file>());
     tools.push_back(std::make_unique<server_tool_edit_file>());
-    tools.push_back(std::make_unique<server_tool_get_datetime>());
     tools.push_back(std::make_unique<server_tool_get_info>());
     return tools;
 }

tools/ui/src/lib/components/app/chat/ChatMessages/ChatMessage/ChatMessageToolCall/ChatMessageToolCallBlockGetDatetime.svelte

@@ -33,7 +33,7 @@
 				if (typeof obj.result === 'string') return { dateString: obj.result.trim() };
 			}
 		} catch {
-			return { dateString: toolResultString.trim() };
+			// not JSON - nothing to show
 		}
 
 		return {};

tools/ui/src/lib/constants/built-in-tools.constants.ts

@@ -34,7 +34,7 @@ export const BUILTIN_TOOL_UI: Readonly<Record<BuiltInTool, BuiltinToolUiEntry>>
 		label: 'Search files',
 		source: ToolSource.BUILTIN
 	},
-	[BuiltInTool.GET_DATETIME]: { icon: Clock, label: 'Current time', source: ToolSource.BUILTIN },
+	[BuiltInTool.GET_DATETIME]: { icon: Clock, label: 'Current time', source: ToolSource.FRONTEND },
 	[BuiltInTool.GET_INFO]: { icon: Info, label: 'Runtime info', source: ToolSource.BUILTIN },
 	[BuiltInTool.GREP_SEARCH]: {
 		icon: SearchCode,

tools/ui/src/lib/constants/get-datetime.ts

@@ -0,0 +1,20 @@
+import { BuiltInTool, JsonSchemaType, ToolCallType } from '$lib/enums';
+import type { OpenAIToolDefinition } from '$lib/types';
+
+export const GET_DATETIME_TOOL_NAME = BuiltInTool.GET_DATETIME;
+
+export function buildGetDatetimeToolDefinition(): OpenAIToolDefinition {
+	return {
+		function: {
+			description:
+				'Returns the current local date and time in ISO 8601 format, with the IANA time zone name',
+			name: GET_DATETIME_TOOL_NAME,
+			parameters: {
+				properties: {},
+				required: [],
+				type: JsonSchemaType.OBJECT
+			}
+		},
+		type: ToolCallType.FUNCTION
+	};
+}

tools/ui/src/lib/constants/index.ts

@@ -59,4 +59,5 @@ export * from './uri-template.constants';
 export * from './url.constants';
 export * from './working-directory.constants';
 export * from './read-media';
+export * from './get-datetime';
 export * from './browser-info';

tools/ui/src/lib/stores/agentic.svelte.ts

@@ -84,7 +84,12 @@ import type {
 	DatabaseMessageExtraAudioFile,
 	DatabaseMessageExtraImageFile
 } from '$lib/types/database';
-import { executeBrowserInfoTool, getAudioInputFormat, isAbortError } from '$lib/utils';
+import {
+	executeBrowserInfoTool,
+	executeGetDatetimeTool,
+	getAudioInputFormat,
+	isAbortError
+} from '$lib/utils';
 import { SvelteMap } from 'svelte/reactivity';
 
 function createDefaultSession(): AgenticSession {
@@ -946,7 +951,9 @@ class AgenticStore {
 
 							let executionResult: ToolExecutionResult;
 
-							if (toolName === BuiltInTool.GET_INFO) {
+							if (toolName === BuiltInTool.GET_DATETIME) {
+								executionResult = executeGetDatetimeTool();
+							} else if (toolName === BuiltInTool.GET_INFO) {
 								executionResult = executeBrowserInfoTool();
 							} else if (toolName === BuiltInTool.READ_MEDIA) {
 								executionResult = await ReadMediaService.executeTool(

tools/ui/src/lib/stores/tools.svelte.ts

@@ -1,6 +1,7 @@
 import { browser } from '$app/environment';
 import {
 	buildBrowserInfoToolDefinition,
+	buildGetDatetimeToolDefinition,
 	buildReadMediaToolDefinition,
 	DISABLED_TOOL_KEYS_LOCALSTORAGE_KEY,
 	HOME_TILDE,
@@ -176,7 +177,7 @@ class ToolsStore {
 	}
 
 	get frontendTools(): OpenAIToolDefinition[] {
-		const tools: OpenAIToolDefinition[] = [];
+		const tools: OpenAIToolDefinition[] = [buildGetDatetimeToolDefinition()];
 
 		if (settingsStore.config.jsSandboxEnabled) {
 			tools.push(buildSandboxToolDefinition(!!settingsStore.config.symbolicMathEnabled));

tools/ui/src/lib/utils/get-datetime.ts

@@ -0,0 +1,38 @@
+/**
+ * Frontend executor for the `get_datetime` tool. It runs in the browser, so it
+ * reports the user's own clock and time zone instead of the server's UTC time -
+ * a chat about "tomorrow" means the user's tomorrow, not the host's.
+ *
+ * @see buildGetDatetimeToolDefinition in constants/get-datetime.ts - tool schema sent to the LLM
+ */
+
+import type { ToolExecutionResult } from '$lib/types';
+
+function pad(value: number): string {
+	return String(value).padStart(2, '0');
+}
+
+/** ISO 8601 in local time, e.g. `2026-08-17T14:05:09+02:00` */
+function localIsoString(date: Date): string {
+	// getTimezoneOffset() counts minutes behind UTC, ISO 8601 counts them ahead
+	const offset = -date.getTimezoneOffset();
+	const sign = offset < 0 ? '-' : '+';
+	const absOffset = Math.abs(offset);
+	const day = `${date.getFullYear()}-${pad(date.getMonth() + 1)}-${pad(date.getDate())}`;
+	const time = `${pad(date.getHours())}:${pad(date.getMinutes())}:${pad(date.getSeconds())}`;
+
+	return `${day}T${time}${sign}${pad(Math.floor(absOffset / 60))}:${pad(absOffset % 60)}`;
+}
+
+/** The `result` field keeps the shape the `get_datetime` renderer already reads. */
+export function executeGetDatetimeTool(): ToolExecutionResult {
+	const now = new Date();
+
+	return {
+		content: JSON.stringify({
+			result: localIsoString(now),
+			timezone: Intl.DateTimeFormat().resolvedOptions().timeZone
+		}),
+		isError: false
+	};
+}

tools/ui/src/lib/utils/index.ts

@@ -331,6 +331,9 @@ export { getChatCommands } from './chat-commands';
 // SANDBOX_TOOL_DEFINITION is deprecated; kept for backward compatibility.
 export { buildSandboxToolDefinition, SANDBOX_TOOL_DEFINITION } from './sandbox-tool';
 
+// Frontend `get_datetime` executor (the browser clock, not the server's)
+export { executeGetDatetimeTool } from './get-datetime';
+
 // Browser fallback for the server's get_info tool
 export { executeBrowserInfoTool } from './browser-info';