diff --git a/src/agents/builtin-agents/hephaestus-agent.ts b/src/agents/builtin-agents/hephaestus-agent.ts
index a32064c63..fc7b3d571 100644
--- a/src/agents/builtin-agents/hephaestus-agent.ts
+++ b/src/agents/builtin-agents/hephaestus-agent.ts
@@ -8,6 +8,7 @@ import { applyEnvironmentContext } from "./environment-context"
 import { applyCategoryOverride, mergeAgentConfig } from "./agent-overrides"
 import { applyModelResolution, getFirstFallbackModel } from "./model-resolution"
 import { getGptApplyPatchPermission } from "../gpt-apply-patch-guard"
+import { getFrontierToolSchemaPermission } from "../frontier-tool-schema-guard"
 
 export function maybeCreateHephaestusConfig(input: {
   disabledAgents: string[]
@@ -89,6 +90,11 @@ export function maybeCreateHephaestusConfig(input: {
   }
 
   const resolvedModel = hephaestusConfig.model ?? ""
+  const frontierDeny = getFrontierToolSchemaPermission(resolvedModel)
+  if (Object.keys(frontierDeny).length > 0 && hephaestusConfig.permission) {
+    Object.assign(hephaestusConfig.permission, frontierDeny)
+  }
+
   const gptDeny = getGptApplyPatchPermission(resolvedModel)
   if (Object.keys(gptDeny).length > 0 && hephaestusConfig.permission) {
     Object.assign(hephaestusConfig.permission, gptDeny)
diff --git a/src/agents/builtin-agents/sisyphus-agent.test.ts b/src/agents/builtin-agents/sisyphus-agent.test.ts
index e7289f6c0..b5d14895a 100644
--- a/src/agents/builtin-agents/sisyphus-agent.test.ts
+++ b/src/agents/builtin-agents/sisyphus-agent.test.ts
@@ -1,3 +1,5 @@
+/// <reference types="bun-types" />
+
 import { describe, expect, test } from "bun:test";
 import { maybeCreateSisyphusConfig } from "./sisyphus-agent";
 import type { AgentOverrides } from "../types";
@@ -12,7 +14,7 @@ describe("maybeCreateSisyphusConfig", () => {
           model: "openai/gpt-5.4",
           permission: {
             apply_patch: "allow",
-          },
+          } as Record<string, "allow">,
         },
       };
       const mergedCategories: Record<string, CategoryConfig> = {};
@@ -46,7 +48,7 @@ describe("maybeCreateSisyphusConfig", () => {
           model: "anthropic/claude-opus-4-7",
           permission: {
             apply_patch: "allow",
-          },
+          } as Record<string, "allow">,
         },
       };
       const mergedCategories: Record<string, CategoryConfig> = {};
@@ -73,6 +75,74 @@ describe("maybeCreateSisyphusConfig", () => {
     });
   });
 
+  describe("#given Opus 4.7 model with user override allowing grep and glob", () => {
+    test("#when config is created #then grep and glob are still denied", () => {
+      // given
+      const agentOverrides: AgentOverrides = {
+        sisyphus: {
+          model: "anthropic/claude-opus-4-7",
+          permission: {
+            grep: "allow",
+            glob: "allow",
+          } as Record<string, "allow">,
+        },
+      };
+      const mergedCategories: Record<string, CategoryConfig> = {};
+
+      // when
+      const config = maybeCreateSisyphusConfig({
+        disabledAgents: [],
+        agentOverrides,
+        availableModels: new Set(["anthropic/claude-opus-4-7"]),
+        systemDefaultModel: "anthropic/claude-opus-4-7",
+        isFirstRunNoCache: false,
+        availableAgents: [],
+        availableSkills: [],
+        availableCategories: [],
+        mergedCategories,
+        useTaskSystem: false,
+      });
+
+      // then
+      expect(config?.permission).toHaveProperty("grep", "deny");
+      expect(config?.permission).toHaveProperty("glob", "deny");
+    });
+  });
+
+  describe("#given GPT 5.5 model with user override allowing grep and glob", () => {
+    test("#when config is created #then grep and glob are still denied", () => {
+      // given
+      const agentOverrides: AgentOverrides = {
+        sisyphus: {
+          model: "openai/gpt-5.5",
+          permission: {
+            grep: "allow",
+            glob: "allow",
+          } as Record<string, "allow">,
+        },
+      };
+      const mergedCategories: Record<string, CategoryConfig> = {};
+
+      // when
+      const config = maybeCreateSisyphusConfig({
+        disabledAgents: [],
+        agentOverrides,
+        availableModels: new Set(["openai/gpt-5.5"]),
+        systemDefaultModel: "openai/gpt-5.5",
+        isFirstRunNoCache: false,
+        availableAgents: [],
+        availableSkills: [],
+        availableCategories: [],
+        mergedCategories,
+        useTaskSystem: false,
+      });
+
+      // then
+      expect(config?.permission).toHaveProperty("grep", "deny");
+      expect(config?.permission).toHaveProperty("glob", "deny");
+    });
+  });
+
   describe("#given generic GPT model with user override allowing apply_patch", () => {
     test("#when config is created #then apply_patch is still denied", () => {
       // given
@@ -81,7 +151,7 @@ describe("maybeCreateSisyphusConfig", () => {
           model: "openai/gpt-4o",
           permission: {
             apply_patch: "allow",
-          },
+          } as Record<string, "allow">,
         },
       };
       const mergedCategories: Record<string, CategoryConfig> = {};
diff --git a/src/agents/builtin-agents/sisyphus-agent.ts b/src/agents/builtin-agents/sisyphus-agent.ts
index 97aef5f61..1b111d6cd 100644
--- a/src/agents/builtin-agents/sisyphus-agent.ts
+++ b/src/agents/builtin-agents/sisyphus-agent.ts
@@ -8,6 +8,7 @@ import { applyOverrides } from "./agent-overrides"
 import { applyModelResolution, getFirstFallbackModel } from "./model-resolution"
 import { createSisyphusAgent } from "../sisyphus"
 import { getGptApplyPatchPermission } from "../gpt-apply-patch-guard"
+import { getFrontierToolSchemaPermission } from "../frontier-tool-schema-guard"
 
 export function maybeCreateSisyphusConfig(input: {
   disabledAgents: string[]
@@ -83,6 +84,11 @@ export function maybeCreateSisyphusConfig(input: {
   sisyphusConfig = applyOverrides(sisyphusConfig, sisyphusOverride, mergedCategories, directory)
 
   const resolvedModel = sisyphusConfig.model ?? ""
+  const frontierDeny = getFrontierToolSchemaPermission(resolvedModel)
+  if (Object.keys(frontierDeny).length > 0 && sisyphusConfig.permission) {
+    Object.assign(sisyphusConfig.permission, frontierDeny)
+  }
+
   const gptDeny = getGptApplyPatchPermission(resolvedModel)
   if (Object.keys(gptDeny).length > 0 && sisyphusConfig.permission) {
     Object.assign(sisyphusConfig.permission, gptDeny)
diff --git a/src/agents/frontier-tool-schema-guard.ts b/src/agents/frontier-tool-schema-guard.ts
new file mode 100644
index 000000000..028943dd8
--- /dev/null
+++ b/src/agents/frontier-tool-schema-guard.ts
@@ -0,0 +1,12 @@
+import { isGpt5_5Model } from "./types"
+
+function isOpus47Model(model: string): boolean {
+  const modelName = model.includes("/") ? (model.split("/").pop() ?? model) : model
+  return modelName.toLowerCase().includes("claude-opus-4-7")
+}
+
+export function getFrontierToolSchemaPermission(model: string): Record<string, "deny"> {
+  return isOpus47Model(model) || isGpt5_5Model(model)
+    ? { grep: "deny" as const, glob: "deny" as const }
+    : {}
+}
diff --git a/src/agents/hephaestus/agent.test.ts b/src/agents/hephaestus/agent.test.ts
index f7d1087f6..22f1d8c81 100644
--- a/src/agents/hephaestus/agent.test.ts
+++ b/src/agents/hephaestus/agent.test.ts
@@ -1,3 +1,5 @@
+/// <reference types="bun-types" />
+
 import { describe, expect, test } from "bun:test";
 import {
   getHephaestusPromptSource,
@@ -321,7 +323,7 @@ describe("maybeCreateHephaestusConfig GPT apply_patch guard", () => {
           model: "openai/gpt-5.4",
           permission: {
             apply_patch: "allow",
-          },
+          } as Record<string, "allow">,
         },
       };
       const mergedCategories: Record<string, CategoryConfig> = {};
@@ -355,7 +357,7 @@ describe("maybeCreateHephaestusConfig GPT apply_patch guard", () => {
           model: "anthropic/claude-opus-4-7",
           permission: {
             apply_patch: "allow",
-          },
+          } as Record<string, "allow">,
         },
       };
       const mergedCategories: Record<string, CategoryConfig> = {};
@@ -389,7 +391,7 @@ describe("maybeCreateHephaestusConfig GPT apply_patch guard", () => {
           model: "openai/gpt-4o",
           permission: {
             apply_patch: "allow",
-          },
+          } as Record<string, "allow">,
         },
       };
       const mergedCategories: Record<string, CategoryConfig> = {};
@@ -414,4 +416,72 @@ describe("maybeCreateHephaestusConfig GPT apply_patch guard", () => {
       expect(config?.permission).toHaveProperty("apply_patch", "deny");
     });
   });
+
+  describe("#given Opus 4.7 model with user override allowing grep and glob", () => {
+    test("#when config is created #then grep and glob are still denied", () => {
+      // given
+      const agentOverrides: AgentOverrides = {
+        hephaestus: {
+          model: "anthropic/claude-opus-4-7",
+          permission: {
+            grep: "allow",
+            glob: "allow",
+          } as Record<string, "allow">,
+        },
+      };
+      const mergedCategories: Record<string, CategoryConfig> = {};
+
+      // when
+      const config = maybeCreateHephaestusConfig({
+        disabledAgents: [],
+        agentOverrides,
+        availableModels: new Set(["anthropic/claude-opus-4-7"]),
+        systemDefaultModel: "anthropic/claude-opus-4-7",
+        isFirstRunNoCache: false,
+        availableAgents: [],
+        availableSkills: [],
+        availableCategories: [],
+        mergedCategories,
+        useTaskSystem: false,
+      });
+
+      // then
+      expect(config?.permission).toHaveProperty("grep", "deny");
+      expect(config?.permission).toHaveProperty("glob", "deny");
+    });
+  });
+
+  describe("#given GPT 5.5 model with user override allowing grep and glob", () => {
+    test("#when config is created #then grep and glob are still denied", () => {
+      // given
+      const agentOverrides: AgentOverrides = {
+        hephaestus: {
+          model: "openai/gpt-5.5",
+          permission: {
+            grep: "allow",
+            glob: "allow",
+          } as Record<string, "allow">,
+        },
+      };
+      const mergedCategories: Record<string, CategoryConfig> = {};
+
+      // when
+      const config = maybeCreateHephaestusConfig({
+        disabledAgents: [],
+        agentOverrides,
+        availableModels: new Set(["openai/gpt-5.5"]),
+        systemDefaultModel: "openai/gpt-5.5",
+        isFirstRunNoCache: false,
+        availableAgents: [],
+        availableSkills: [],
+        availableCategories: [],
+        mergedCategories,
+        useTaskSystem: false,
+      });
+
+      // then
+      expect(config?.permission).toHaveProperty("grep", "deny");
+      expect(config?.permission).toHaveProperty("glob", "deny");
+    });
+  });
 });
diff --git a/src/agents/hephaestus/agent.ts b/src/agents/hephaestus/agent.ts
index b348f30b7..3aa773bac 100644
--- a/src/agents/hephaestus/agent.ts
+++ b/src/agents/hephaestus/agent.ts
@@ -9,6 +9,7 @@ import type {
 } from "../dynamic-agent-prompt-builder";
 import { categorizeTools, buildAgentIdentitySection } from "../dynamic-agent-prompt-builder";
 import { getGptApplyPatchPermission } from "../gpt-apply-patch-guard";
+import { getFrontierToolSchemaPermission } from "../frontier-tool-schema-guard";
 
 import { buildHephaestusPrompt as buildGptPrompt } from "./gpt";
 import { buildHephaestusPrompt as buildGpt53CodexPrompt } from "./gpt-5-3-codex";
@@ -139,6 +140,7 @@ export function createHephaestusAgent(
     permission: {
       question: "allow",
       call_omo_agent: "deny",
+      ...getFrontierToolSchemaPermission(model),
       ...getGptApplyPatchPermission(model),
     } as AgentConfig["permission"],
     reasoningEffort: "medium",
diff --git a/src/agents/sisyphus.ts b/src/agents/sisyphus.ts
index 21a36b8a0..d0bfb0979 100644
--- a/src/agents/sisyphus.ts
+++ b/src/agents/sisyphus.ts
@@ -13,6 +13,7 @@ import { buildGpt54SisyphusPrompt } from "./sisyphus/gpt-5-4";
 import { buildGpt55SisyphusPrompt } from "./sisyphus/gpt-5-5";
 import { buildTaskManagementSection } from "./sisyphus/default";
 import { getGptApplyPatchPermission } from "./gpt-apply-patch-guard";
+import { getFrontierToolSchemaPermission } from "./frontier-tool-schema-guard";
 
 const MODE: AgentMode = "primary";
 export const SISYPHUS_PROMPT_METADATA: AgentPromptMetadata = {
@@ -501,6 +502,7 @@ export function createSisyphusAgent(
       permission: {
         question: "allow",
         call_omo_agent: "deny",
+        ...getFrontierToolSchemaPermission(model),
         ...getGptApplyPatchPermission(model),
       } as AgentConfig["permission"],
       reasoningEffort: "medium",
@@ -527,6 +529,7 @@ export function createSisyphusAgent(
       permission: {
         question: "allow",
         call_omo_agent: "deny",
+        ...getFrontierToolSchemaPermission(model),
         ...getGptApplyPatchPermission(model),
       } as AgentConfig["permission"],
       reasoningEffort: "medium",
@@ -567,6 +570,7 @@ export function createSisyphusAgent(
   const permission = {
     question: "allow",
     call_omo_agent: "deny",
+    ...getFrontierToolSchemaPermission(model),
     ...getGptApplyPatchPermission(model),
   } as AgentConfig["permission"];
   const base = {
diff --git a/src/agents/tool-restrictions.test.ts b/src/agents/tool-restrictions.test.ts
index 3ae7bfcfe..1d0fed4fd 100644
--- a/src/agents/tool-restrictions.test.ts
+++ b/src/agents/tool-restrictions.test.ts
@@ -1,3 +1,5 @@
+/// <reference types="bun-types" />
+
 import { describe, test, expect } from "bun:test"
 import { createOracleAgent } from "./oracle"
 import { createLibrarianAgent } from "./librarian"
@@ -6,6 +8,7 @@ import { createMomusAgent } from "./momus"
 import { createMetisAgent } from "./metis"
 import { createAtlasAgent } from "./atlas"
 import { createSisyphusAgent } from "./sisyphus"
+import { createHephaestusAgent } from "./hephaestus"
 
 const TEST_MODEL = "anthropic/claude-sonnet-4-5"
 
@@ -131,4 +134,47 @@ describe("read-only agent tool restrictions", () => {
       expect(claudePermission["apply_patch"]).toBeUndefined()
     })
   })
+
+  describe("Sisyphus and Hephaestus frontier tool schema restrictions", () => {
+    test("deny grep and glob for Opus 4.7 and GPT 5.5 models", () => {
+      // given
+      const frontierAgents = [
+        createSisyphusAgent("anthropic/claude-opus-4-7"),
+        createSisyphusAgent("openai/gpt-5.5"),
+        createHephaestusAgent("anthropic/claude-opus-4-7"),
+        createHephaestusAgent("openai/gpt-5.5"),
+      ]
+
+      // when
+      const permissions = frontierAgents.map(
+        (agent) => (agent.permission ?? {}) as Record<string, string>,
+      )
+
+      // then
+      for (const permission of permissions) {
+        expect(permission.grep).toBe("deny")
+        expect(permission.glob).toBe("deny")
+      }
+    })
+
+    test("keeps grep and glob available for other models", () => {
+      // given
+      const otherAgents = [
+        createSisyphusAgent("anthropic/claude-sonnet-4-5"),
+        createSisyphusAgent("openai/gpt-5.4"),
+        createHephaestusAgent("openai/gpt-5.4"),
+      ]
+
+      // when
+      const permissions = otherAgents.map(
+        (agent) => (agent.permission ?? {}) as Record<string, string>,
+      )
+
+      // then
+      for (const permission of permissions) {
+        expect(permission.grep).toBeUndefined()
+        expect(permission.glob).toBeUndefined()
+      }
+    })
+  })
 })