diff --git a/src/resources/extensions/gsd/tests/subagent-agent-discovery.test.ts b/src/resources/extensions/gsd/tests/subagent-agent-discovery.test.ts
index 14cf587e5..5d8a6bd12 100644
--- a/src/resources/extensions/gsd/tests/subagent-agent-discovery.test.ts
+++ b/src/resources/extensions/gsd/tests/subagent-agent-discovery.test.ts
@@ -42,3 +42,50 @@ test("discoverAgents falls back to legacy .pi/agents when needed", (t) => {
 	assert.equal(discovery.projectAgentsDir, agentsDir);
 	assert.deepEqual(discovery.agents.map((agent) => agent.name), ["ping"]);
 });
+
+test("discoverAgents accepts tools frontmatter as a YAML list", (t) => {
+	const root = makeProjectRoot(t);
+	const agentsDir = join(root, ".gsd", "agents");
+	mkdirSync(agentsDir, { recursive: true });
+	writeFileSync(
+		join(agentsDir, "reviewer.md"),
+		[
+			"---",
+			"name: reviewer",
+			"description: review agent",
+			"tools:",
+			"  - bash",
+			"  - read",
+			"---",
+			"Review code",
+			"",
+		].join("\n"),
+	);
+
+	const discovery = discoverAgents(root, "project");
+
+	assert.deepEqual(discovery.agents.map((agent) => agent.name), ["reviewer"]);
+	assert.deepEqual(discovery.agents[0]?.tools, ["bash", "read"]);
+});
+
+test("discoverAgents still accepts comma-separated tools frontmatter", (t) => {
+	const root = makeProjectRoot(t);
+	const agentsDir = join(root, ".gsd", "agents");
+	mkdirSync(agentsDir, { recursive: true });
+	writeFileSync(
+		join(agentsDir, "reviewer.md"),
+		[
+			"---",
+			"name: reviewer",
+			"description: review agent",
+			"tools: bash, read",
+			"---",
+			"Review code",
+			"",
+		].join("\n"),
+	);
+
+	const discovery = discoverAgents(root, "project");
+
+	assert.deepEqual(discovery.agents[0]?.tools, ["bash", "read"]);
+});
diff --git a/src/resources/extensions/subagent/agents.ts b/src/resources/extensions/subagent/agents.ts
index 43e124fa3..6f14c3bcf 100644
--- a/src/resources/extensions/subagent/agents.ts
+++ b/src/resources/extensions/subagent/agents.ts
@@ -25,6 +25,33 @@ export interface AgentDiscoveryResult {
 	projectAgentsDir: string | null;
 }
 
+interface AgentFrontmatter extends Record<string, unknown> {
+	name?: string;
+	description?: string;
+	tools?: string | string[];
+	model?: string;
+}
+
+function parseAgentTools(value: string | string[] | undefined): string[] | undefined {
+	if (typeof value === "string") {
+		const tools = value
+			.split(",")
+			.map((tool) => tool.trim())
+			.filter(Boolean);
+		return tools.length > 0 ? tools : undefined;
+	}
+
+	if (Array.isArray(value)) {
+		const tools = value
+			.flatMap((tool) => typeof tool === "string" ? tool.split(",") : [])
+			.map((tool) => tool.trim())
+			.filter(Boolean);
+		return tools.length > 0 ? tools : undefined;
+	}
+
+	return undefined;
+}
+
 function loadAgentsFromDir(dir: string, source: "user" | "project"): AgentConfig[] {
 	const agents: AgentConfig[] = [];
 
@@ -51,16 +78,13 @@ function loadAgentsFromDir(dir: string, source: "user" | "project"): AgentConfig
 			continue;
 		}
 
-		const { frontmatter, body } = parseFrontmatter<Record<string, string>>(content);
+		const { frontmatter, body } = parseFrontmatter<AgentFrontmatter>(content);
 
-		if (!frontmatter.name || !frontmatter.description) {
+		if (typeof frontmatter.name !== "string" || typeof frontmatter.description !== "string") {
 			continue;
 		}
 
-		const tools = frontmatter.tools
-			?.split(",")
-			.map((t: string) => t.trim())
-			.filter(Boolean);
+		const tools = parseAgentTools(frontmatter.tools);
 
 		agents.push({
 			name: frontmatter.name,