diff --git a/.env.example b/.env.example
index 6540c58..6ea2837 100644
--- a/.env.example
+++ b/.env.example
@@ -14,6 +14,10 @@ LETTA_API_KEY=your_letta_api_key
 # Allowed tools (comma-separated)
 # ALLOWED_TOOLS=Read,Glob,Grep,Task,web_search,conversation_search
 
+# Disallowed tools (comma-separated)
+# Default blocks plan-mode interactive tools that can stall headless agents
+# DISALLOWED_TOOLS=EnterPlanMode,ExitPlanMode
+
 # ============================================
 # Telegram (required: at least one channel)
 # ============================================
diff --git a/src/core/bot.ts b/src/core/bot.ts
index b8ed142..d272db1 100644
--- a/src/core/bot.ts
+++ b/src/core/bot.ts
@@ -151,11 +151,20 @@ export class LettaBot implements AgentSession {
   // =========================================================================
 
   private get baseSessionOptions() {
+    const disallowedTools = this.config.disallowedTools || [];
+
     return {
       permissionMode: 'bypassPermissions' as const,
       allowedTools: this.config.allowedTools,
+      disallowedTools,
       cwd: this.config.workingDir,
       canUseTool: (toolName: string, _toolInput: Record<string, unknown>) => {
+        if (disallowedTools.includes(toolName)) {
+          return {
+            behavior: 'deny' as const,
+            message: `Tool '${toolName}' is blocked by bot configuration`,
+          };
+        }
         console.log(`[Bot] Tool approval requested: ${toolName} (should be auto-approved by bypassPermissions)`);
         return { behavior: 'allow' as const };
       },
diff --git a/src/core/types.ts b/src/core/types.ts
index 5616ce7..74157f4 100644
--- a/src/core/types.ts
+++ b/src/core/types.ts
@@ -124,6 +124,7 @@ export interface BotConfig {
   workingDir: string;
   agentName?: string; // Name for the agent (set via API after creation)
   allowedTools: string[];
+  disallowedTools?: string[];
 
   // Display
   displayName?: string; // Prefix outbound messages (e.g. "💜 Signo")
diff --git a/src/main.ts b/src/main.ts
index d1c0677..7f98e8b 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -397,10 +397,22 @@ function createGroupBatcher(
 
 // Skills are installed to agent-scoped directory when agent is created (see core/bot.ts)
 
+function parseCsvList(raw: string): string[] {
+  return raw
+    .split(',')
+    .map((item) => item.trim())
+    .filter((item) => item.length > 0);
+}
+
 // Global config (shared across all agents)
 const globalConfig = {
   workingDir: getWorkingDir(),
-  allowedTools: (process.env.ALLOWED_TOOLS || 'Bash,Read,Edit,Write,Glob,Grep,Task,web_search,conversation_search').split(','),
+  allowedTools: parseCsvList(
+    process.env.ALLOWED_TOOLS || 'Bash,Read,Edit,Write,Glob,Grep,Task,web_search,conversation_search',
+  ),
+  disallowedTools: parseCsvList(
+    process.env.DISALLOWED_TOOLS || 'EnterPlanMode,ExitPlanMode',
+  ),
   attachmentsMaxBytes: resolveAttachmentsMaxBytes(),
   attachmentsMaxAgeDays: resolveAttachmentsMaxAgeDays(),
   cronEnabled: process.env.CRON_ENABLED === 'true',  // Legacy env var fallback
@@ -472,6 +484,7 @@ async function main() {
       workingDir: globalConfig.workingDir,
       agentName: agentConfig.name,
       allowedTools: globalConfig.allowedTools,
+      disallowedTools: globalConfig.disallowedTools,
       displayName: agentConfig.displayName,
       maxToolCalls: agentConfig.features?.maxToolCalls,
       skills: {