diff --git a/src/agents/builtin-agents.ts b/src/agents/builtin-agents.ts
index 350d69e54..0175bcaa9 100644
--- a/src/agents/builtin-agents.ts
+++ b/src/agents/builtin-agents.ts
@@ -26,7 +26,6 @@ import { collectPendingBuiltinAgents } from "./builtin-agents/general-agents"
 import { maybeCreateSisyphusConfig } from "./builtin-agents/sisyphus-agent"
 import { maybeCreateHephaestusConfig } from "./builtin-agents/hephaestus-agent"
 import { maybeCreateAtlasConfig } from "./builtin-agents/atlas-agent"
-import { buildCustomAgentMetadata, parseRegisteredAgentSummaries } from "./custom-agent-summaries"
 
 type AgentSource = AgentFactory | AgentConfig
 
@@ -120,23 +119,6 @@ export async function createBuiltinAgents(
     disableOmoEnv,
   })
 
-  const registeredAgents = parseRegisteredAgentSummaries(customAgentSummaries)
-  const builtinAgentNames = new Set(Object.keys(agentSources).map((name) => name.toLowerCase()))
-  const disabledAgentNames = new Set(disabledAgents.map((name) => name.toLowerCase()))
-
-  for (const agent of registeredAgents) {
-    const lowerName = agent.name.toLowerCase()
-    if (builtinAgentNames.has(lowerName)) continue
-    if (disabledAgentNames.has(lowerName)) continue
-    if (availableAgents.some((availableAgent) => availableAgent.name.toLowerCase() === lowerName)) continue
-
-    availableAgents.push({
-      name: agent.name,
-      description: agent.description,
-      metadata: buildCustomAgentMetadata(agent.name, agent.description),
-    })
-  }
-
   const sisyphusConfig = maybeCreateSisyphusConfig({
     disabledAgents,
     agentOverrides,
diff --git a/src/agents/custom-agent-orchestrator-visibility.test.ts b/src/agents/custom-agent-orchestrator-visibility.test.ts
new file mode 100644
index 000000000..c0b709e4b
--- /dev/null
+++ b/src/agents/custom-agent-orchestrator-visibility.test.ts
@@ -0,0 +1,40 @@
+import { describe, expect, spyOn, test } from "bun:test"
+import { createBuiltinAgents } from "./builtin-agents"
+import * as shared from "../shared"
+
+const TEST_DEFAULT_MODEL = "anthropic/claude-opus-4-6"
+
+describe("createBuiltinAgents custom agent visibility", () => {
+	test("#given runtime custom agents #when orchestrator prompts are built #then custom agents are not advertised for automatic delegation", async () => {
+		//#given
+		const fetchSpy = spyOn(shared, "fetchAvailableModels").mockResolvedValue(
+			new Set(["anthropic/claude-opus-4-6", "openai/gpt-5.4"])
+		)
+
+		try {
+			//#when
+			const agents = await createBuiltinAgents(
+				[],
+				{},
+				undefined,
+				TEST_DEFAULT_MODEL,
+				undefined,
+				undefined,
+				[],
+				[
+					{
+						name: "backend-engineer",
+						description: "Custom backend specialist",
+					},
+				]
+			)
+
+			//#then
+			expect(agents.sisyphus.prompt).not.toContain("backend-engineer")
+			expect(agents.hephaestus.prompt).not.toContain("backend-engineer")
+			expect(agents.atlas.prompt).not.toContain("backend-engineer")
+		} finally {
+			fetchSpy.mockRestore()
+		}
+	})
+})
diff --git a/src/agents/utils.test.ts b/src/agents/utils.test.ts
index 7b606e5e4..a37a8c710 100644
--- a/src/agents/utils.test.ts
+++ b/src/agents/utils.test.ts
@@ -278,7 +278,7 @@ describe("createBuiltinAgents with model overrides", () => {
     fetchSpy.mockRestore()
   })
 
-  test("includes custom agents in orchestrator prompts when provided via config", async () => {
+  test("does not advertise custom agents in orchestrator prompts when provided via config", async () => {
     // #given
     const fetchSpy = spyOn(shared, "fetchAvailableModels").mockResolvedValue(
       new Set([
@@ -313,9 +313,9 @@ describe("createBuiltinAgents with model overrides", () => {
       )
 
       // #then
-      expect(agents.sisyphus.prompt).toContain("researcher")
-      expect(agents.hephaestus.prompt).toContain("researcher")
-      expect(agents.atlas.prompt).toContain("researcher")
+      expect(agents.sisyphus.prompt).not.toContain("researcher")
+      expect(agents.hephaestus.prompt).not.toContain("researcher")
+      expect(agents.atlas.prompt).not.toContain("researcher")
     } finally {
       fetchSpy.mockRestore()
     }
@@ -429,7 +429,7 @@ describe("createBuiltinAgents with model overrides", () => {
     }
   })
 
-  test("deduplicates custom agents case-insensitively", async () => {
+  test("does not advertise duplicate custom agents case-insensitively", async () => {
     // #given
     const fetchSpy = spyOn(shared, "fetchAvailableModels").mockResolvedValue(
       new Set(["anthropic/claude-opus-4-6", "openai/gpt-5.4"])
@@ -455,13 +455,13 @@ describe("createBuiltinAgents with model overrides", () => {
 
       // #then
       const matches = (agents.sisyphus?.prompt ?? "").match(/Custom agent: researcher/gi) ?? []
-      expect(matches.length).toBe(1)
+      expect(matches.length).toBe(0)
     } finally {
       fetchSpy.mockRestore()
     }
   })
 
-  test("sanitizes custom agent strings for markdown tables", async () => {
+  test("does not surface custom agent strings in orchestrator prompts", async () => {
     // #given
     const fetchSpy = spyOn(shared, "fetchAvailableModels").mockResolvedValue(
       new Set(["anthropic/claude-opus-4-6", "openai/gpt-5.4"])
@@ -488,7 +488,7 @@ describe("createBuiltinAgents with model overrides", () => {
       )
 
       // #then
-      expect(agents.sisyphus.prompt).toContain("Line1 Alpha \\| Beta")
+      expect(agents.sisyphus.prompt).not.toContain("Line1 Alpha \\| Beta")
     } finally {
       fetchSpy.mockRestore()
     }