diff --git a/site/src/pages/AgentsPage/components/ChatElements/ModelSelector.tsx b/site/src/pages/AgentsPage/components/ChatElements/ModelSelector.tsx
index 4b56f0774565b..7a54115d699f0 100644
--- a/site/src/pages/AgentsPage/components/ChatElements/ModelSelector.tsx
+++ b/site/src/pages/AgentsPage/components/ChatElements/ModelSelector.tsx
@@ -68,7 +68,7 @@ interface ModelSelectorProps {
 	onReasoningEffortChange?: (value: string) => void;
 }
 
-const formatContextLimit = (tokens: number): string => {
+export const formatContextLimit = (tokens: number): string => {
 	if (tokens >= 1_000_000) {
 		const m = tokens / 1_000_000;
 		return `${Number.isInteger(m) ? m : m.toFixed(1)}M`;
diff --git a/site/src/pages/AgentsPage/components/ChatElements/tools/ListSubagentModelsTool.tsx b/site/src/pages/AgentsPage/components/ChatElements/tools/ListSubagentModelsTool.tsx
new file mode 100644
index 0000000000000..7c78424f6601f
--- /dev/null
+++ b/site/src/pages/AgentsPage/components/ChatElements/tools/ListSubagentModelsTool.tsx
@@ -0,0 +1,140 @@
+import type React from "react";
+import { ScrollArea } from "#/components/ScrollArea/ScrollArea";
+import { ProviderIcon } from "#/pages/AISettingsPage/ProvidersPage/components/ProviderIcon";
+import { formatProviderLabel } from "#/utils/aiProviders";
+import { formatContextLimit } from "../ModelSelector";
+import { ToolCall } from "./ToolCall";
+import { asNumber, asRecord, asString, type ToolStatus } from "./utils";
+
+const ModelRow: React.FC<{ model: unknown }> = ({ model }) => {
+	const rec = asRecord(model);
+	if (!rec) {
+		return null;
+	}
+	const displayName = asString(rec.display_name).trim();
+	const modelName = asString(rec.model).trim();
+	const contextLimit = asNumber(rec.context_limit);
+	const context =
+		contextLimit !== undefined && contextLimit > 0
+			? formatContextLimit(contextLimit)
+			: "";
+	const efforts = Array.isArray(rec.reasoning_efforts)
+		? rec.reasoning_efforts.map(asString).filter((effort) => effort.trim())
+		: [];
+	const effortRange =
+		efforts.length > 1
+			? `${efforts[0]} - ${efforts[efforts.length - 1]}`
+			: (efforts[0] ?? "");
+	const title = displayName || modelName || "Unknown model";
+
+	return (
+		<div className="grid grid-cols-[minmax(0,1fr)_96px_56px] items-center gap-x-2 px-2 py-1">
+			<span className="min-w-0 truncate text-xs font-medium leading-[18px] text-content-primary">
+				{title}
+			</span>
+			{effortRange ? (
+				<span className="shrink-0 text-right text-xs font-normal leading-[18px] tabular-nums text-content-secondary">
+					{effortRange}
+				</span>
+			) : (
+				<span aria-hidden="true" />
+			)}
+			{context ? (
+				<span className="shrink-0 text-right text-xs font-normal leading-[18px] tabular-nums text-content-secondary">
+					({context})
+				</span>
+			) : (
+				<span aria-hidden="true" />
+			)}
+		</div>
+	);
+};
+
+const ListSubagentModelsContent: React.FC<{ models: unknown[] }> = ({
+	models,
+}) => {
+	// Group by provider like the model picker so models from one provider
+	// sit under a single headed section instead of a flat list.
+	const grouped = new Map<string, unknown[]>();
+	for (const model of models) {
+		const rec = asRecord(model);
+		if (!rec) {
+			continue;
+		}
+		const provider = asString(rec.provider).trim() || "unknown";
+		const group = grouped.get(provider);
+		if (group) {
+			group.push(model);
+			continue;
+		}
+		grouped.set(provider, [model]);
+	}
+
+	return (
+		<ScrollArea
+			className="mt-1.5 rounded-md border border-solid border-border-default"
+			viewportClassName="max-h-64"
+			scrollBarClassName="w-1.5"
+		>
+			<div className="px-1 py-1">
+				{Array.from(grouped.entries(), ([provider, providerModels], index) => (
+					<div
+						key={provider}
+						className={
+							index > 0
+								? "border-0 border-t border-solid border-border-default"
+								: undefined
+						}
+					>
+						<div className="flex items-center gap-1.5 px-2 py-1">
+							<ProviderIcon provider={provider} className="size-3.5" />
+							<span className="text-xs font-semibold leading-[18px] text-content-secondary">
+								{formatProviderLabel(provider)}
+							</span>
+						</div>
+						{providerModels.map((model, modelIndex) => {
+							const rec = asRecord(model);
+							const configID = rec ? asString(rec.model_config_id).trim() : "";
+							return <ModelRow key={configID || modelIndex} model={model} />;
+						})}
+					</div>
+				))}
+			</div>
+		</ScrollArea>
+	);
+};
+
+/**
+ * Collapsed-by-default rendering for `list_subagent_models` tool calls.
+ * Shows "Listed N subagent models" with a chevron; expanding reveals the
+ * models accepted by spawn_agent's model_config_id argument, grouped by
+ * provider like the chat model picker.
+ */
+export const ListSubagentModelsTool: React.FC<{
+	models: unknown[];
+	status: ToolStatus;
+	isError: boolean;
+	errorMessage?: string;
+}> = ({ models, status, isError, errorMessage }) => {
+	const hasContent = models.length > 0;
+	const isRunning = status === "running";
+
+	const label = isRunning
+		? "Listing subagent models…"
+		: `Listed ${models.length} subagent ${models.length === 1 ? "model" : "models"}`;
+
+	return (
+		<ToolCall.Root
+			className="max-w-sm"
+			status={status}
+			isError={isError}
+			errorMessage={errorMessage || "Failed to list subagent models"}
+			hasContent={hasContent}
+		>
+			<ToolCall.Header iconName="list_subagent_models" label={label} />
+			<ToolCall.Content>
+				<ListSubagentModelsContent models={models} />
+			</ToolCall.Content>
+		</ToolCall.Root>
+	);
+};
diff --git a/site/src/pages/AgentsPage/components/ChatElements/tools/Tool.stories.tsx b/site/src/pages/AgentsPage/components/ChatElements/tools/Tool.stories.tsx
index 3f6fd0b45e46d..89f51604dc3c3 100644
--- a/site/src/pages/AgentsPage/components/ChatElements/tools/Tool.stories.tsx
+++ b/site/src/pages/AgentsPage/components/ChatElements/tools/Tool.stories.tsx
@@ -138,6 +138,20 @@ const allToolShowcaseItems: ToolShowcaseItem[] = [
 			total: 1,
 		},
 	},
+	{
+		name: "list_subagent_models",
+		result: {
+			models: [
+				{
+					model_config_id: "model-1",
+					display_name: "Fast Model",
+					model: "fast-1",
+					provider: "openai",
+					is_default: true,
+				},
+			],
+		},
+	},
 	{
 		name: "read_template",
 		args: { template_id: "template-1" },
@@ -1324,6 +1338,117 @@ export const ListAgentsError: Story = {
 	},
 };
 
+// ---------------------------------------------------------------------------
+// ListSubagentModels stories
+// ---------------------------------------------------------------------------
+
+export const ListSubagentModelsCompleted: Story = {
+	args: {
+		name: "list_subagent_models",
+		status: "completed",
+		args: {},
+		result: {
+			models: [
+				{
+					model_config_id: "10000000-0000-0000-0000-000000000001",
+					display_name: "Fast Model",
+					model: "fast-1",
+					provider: "openai",
+					context_limit: 200_000,
+					is_default: true,
+					reasoning_efforts: ["low", "medium", "high"],
+				},
+				{
+					model_config_id: "20000000-0000-0000-0000-000000000002",
+					display_name: "Large Model",
+					model: "large-2",
+					provider: "anthropic",
+					context_limit: 1_000_000,
+					is_default: false,
+					reasoning_efforts: [
+						"none",
+						"minimal",
+						"low",
+						"medium",
+						"high",
+						"xhigh",
+						"max",
+					],
+				},
+				{
+					model_config_id: "30000000-0000-0000-0000-000000000003",
+					display_name: "",
+					model: "gemini-3.6-flash",
+					provider: "google",
+					context_limit: 262_000,
+					is_default: false,
+				},
+			],
+		},
+	},
+	play: async ({ canvasElement }) => {
+		const canvas = within(canvasElement);
+		const header = canvas.getByRole("button", {
+			name: /Listed 3 subagent models/,
+		});
+		expect(header).toBeInTheDocument();
+		await userEvent.click(header);
+		expect(canvas.getByText("OpenAI")).toBeInTheDocument();
+		expect(canvas.getByText("Anthropic")).toBeInTheDocument();
+		expect(canvas.getByText("Google")).toBeInTheDocument();
+		expect(canvas.getByText("Fast Model")).toBeInTheDocument();
+		expect(canvas.getByText("(200K)")).toBeInTheDocument();
+		expect(canvas.getByText("low - high")).toBeInTheDocument();
+		expect(canvas.getByText("Large Model")).toBeInTheDocument();
+		expect(canvas.getByText("(1M)")).toBeInTheDocument();
+		expect(canvas.getByText("none - max")).toBeInTheDocument();
+		expect(canvas.getByText("(262K)")).toBeInTheDocument();
+		expect(canvas.getByText("gemini-3.6-flash")).toBeInTheDocument();
+	},
+};
+
+export const ListSubagentModelsRunning: Story = {
+	args: {
+		name: "list_subagent_models",
+		status: "running",
+		args: {},
+		result: undefined,
+	},
+	play: async ({ canvasElement }) => {
+		const canvas = within(canvasElement);
+		expect(canvas.getByText("Listing subagent models…")).toBeInTheDocument();
+	},
+};
+
+export const ListSubagentModelsEmpty: Story = {
+	args: {
+		name: "list_subagent_models",
+		status: "completed",
+		args: {},
+		result: {
+			models: [],
+		},
+	},
+	play: async ({ canvasElement }) => {
+		const canvas = within(canvasElement);
+		expect(canvas.getByText("Listed 0 subagent models")).toBeInTheDocument();
+	},
+};
+
+export const ListSubagentModelsError: Story = {
+	args: {
+		name: "list_subagent_models",
+		status: "error",
+		isError: true,
+		args: {},
+		result: "list_subagent_models is only available on root chats",
+	},
+	play: async ({ canvasElement }) => {
+		const canvas = within(canvasElement);
+		expect(canvas.getByText("Listed 0 subagent models")).toBeInTheDocument();
+	},
+};
+
 // ---------------------------------------------------------------------------
 // ListTemplates stories
 // ---------------------------------------------------------------------------
diff --git a/site/src/pages/AgentsPage/components/ChatElements/tools/Tool.tsx b/site/src/pages/AgentsPage/components/ChatElements/tools/Tool.tsx
index 299716a156edb..58e38f35d1373 100644
--- a/site/src/pages/AgentsPage/components/ChatElements/tools/Tool.tsx
+++ b/site/src/pages/AgentsPage/components/ChatElements/tools/Tool.tsx
@@ -16,6 +16,7 @@ import { DiffFileHeader } from "./DiffFileHeader";
 import { EditFilesTool } from "./EditFilesTool";
 import { ExecuteTool as ExecuteToolComponent } from "./ExecuteTool";
 import { ListAgentsTool } from "./ListAgentsTool";
+import { ListSubagentModelsTool } from "./ListSubagentModelsTool";
 import { ListTemplatesTool } from "./ListTemplatesTool";
 import { ProcessOutputTool } from "./ProcessOutputTool";
 import { ProposePlanTool } from "./ProposePlanTool";
@@ -573,6 +574,24 @@ const ListAgentsRenderer: FC<ToolRendererProps> = ({
 	);
 };
 
+const ListSubagentModelsRenderer: FC<ToolRendererProps> = ({
+	status,
+	result,
+	isError,
+}) => {
+	const rec = asRecord(result);
+	const models = rec && Array.isArray(rec.models) ? rec.models : [];
+
+	return (
+		<ListSubagentModelsTool
+			models={models}
+			status={status}
+			isError={isError}
+			errorMessage={rec ? asString(rec.error || rec.message) : undefined}
+		/>
+	);
+};
+
 const ReadTemplateRenderer: FC<ToolRendererProps> = ({
 	status,
 	result,
@@ -1024,6 +1043,7 @@ export const toolRenderers: Record<string, FC<ToolRendererProps>> = {
 	start_workspace: StartWorkspaceRenderer,
 	list_templates: ListTemplatesRenderer,
 	list_agents: ListAgentsRenderer,
+	list_subagent_models: ListSubagentModelsRenderer,
 	read_template: ReadTemplateRenderer,
 	read_skill: ReadSkillRenderer,
 	read_skill_file: ReadSkillFileRenderer,
diff --git a/site/src/pages/AgentsPage/components/ChatElements/tools/ToolIcon.tsx b/site/src/pages/AgentsPage/components/ChatElements/tools/ToolIcon.tsx
index b74f26d14835c..0d5cc6448b32d 100644
--- a/site/src/pages/AgentsPage/components/ChatElements/tools/ToolIcon.tsx
+++ b/site/src/pages/AgentsPage/components/ChatElements/tools/ToolIcon.tsx
@@ -38,6 +38,7 @@ export const toolIcons: Partial<Record<string, LucideIcon>> = {
 	start_workspace: PowerIcon,
 	chat_summarized: BotIcon,
 	list_agents: BotIcon,
+	list_subagent_models: BotIcon,
 	thinking: LightbulbIcon,
 	propose_plan: RouteIcon,
 	ask_user_question: BadgeQuestionMarkIcon,