diff --git a/docs/automation/cron-vs-heartbeat.md b/docs/automation/cron-vs-heartbeat.md
index 333a45d0b..325575602 100644
--- a/docs/automation/cron-vs-heartbeat.md
+++ b/docs/automation/cron-vs-heartbeat.md
@@ -201,7 +201,7 @@ For ad-hoc workflows, call Lobster directly.
 
 - Lobster runs as a **local subprocess** (`lobster` CLI) in tool mode and returns a **JSON envelope**.
 - If the tool returns `needs_approval`, you resume with a `resumeToken` and `approve` flag.
-- The tool is an **optional plugin**; you must allowlist `lobster` in `tools.allow`.
+- The tool is an **optional plugin**; enable it additively via `tools.alsoAllow: ["lobster"]` (recommended).
 - If you pass `lobsterPath`, it must be an **absolute path**.
 
 See [Lobster](/tools/lobster) for full usage and examples.
diff --git a/docs/tools/lobster.md b/docs/tools/lobster.md
index daf04fd39..f4718c4b5 100644
--- a/docs/tools/lobster.md
+++ b/docs/tools/lobster.md
@@ -158,7 +158,19 @@ If you want to use a custom binary location, pass an **absolute** `lobsterPath`
 
 ## Enable the tool
 
-Lobster is an **optional** plugin tool (not enabled by default). Allow it per agent:
+Lobster is an **optional** plugin tool (not enabled by default).
+
+Recommended (additive, safe):
+
+```json
+{
+  "tools": {
+    "alsoAllow": ["lobster"]
+  }
+}
+```
+
+Or per-agent:
 
 ```json
 {
@@ -167,7 +179,7 @@ Lobster is an **optional** plugin tool (not enabled by default). Allow it per ag
       {
         "id": "main",
         "tools": {
-          "allow": ["lobster"]
+          "alsoAllow": ["lobster"]
         }
       }
     ]
@@ -175,7 +187,7 @@ Lobster is an **optional** plugin tool (not enabled by default). Allow it per ag
 }
 ```
 
-You can also allow it globally with `tools.allow` if every agent should see it.
+Avoid using `tools.allow: ["lobster"]` unless you intend to run in restrictive allowlist mode.
 
 Note: allowlists are opt-in for optional plugins. If your allowlist only names
 plugin tools (like `lobster`), Clawdbot keeps core tools enabled. To restrict core
diff --git a/src/agents/pi-tools.ts b/src/agents/pi-tools.ts
index 6f293514d..4a0bebed0 100644
--- a/src/agents/pi-tools.ts
+++ b/src/agents/pi-tools.ts
@@ -346,7 +346,7 @@ export function createClawdbotCodingTools(options?: {
     if (resolved.unknownAllowlist.length > 0) {
       const entries = resolved.unknownAllowlist.join(", ");
       const suffix = resolved.strippedAllowlist
-        ? "Ignoring allowlist so core tools remain available."
+        ? "Ignoring allowlist so core tools remain available. Use tools.alsoAllow for additive plugin tool enablement."
         : "These entries won't match any tool unless the plugin is enabled.";
       logWarn(`tools: ${label} allowlist contains unknown entries (${entries}). ${suffix}`);
     }
diff --git a/src/agents/tool-policy.ts b/src/agents/tool-policy.ts
index ac2b1a91c..85152069e 100644
--- a/src/agents/tool-policy.ts
+++ b/src/agents/tool-policy.ts
@@ -209,6 +209,12 @@ export function stripPluginOnlyAllowlist(
     if (!isCoreEntry && !isPluginEntry) unknownAllowlist.push(entry);
   }
   const strippedAllowlist = !hasCoreEntry;
+  // When an allowlist contains only plugin tools, we strip it to avoid accidentally
+  // disabling core tools. Users who want additive behavior should prefer `tools.alsoAllow`.
+  if (strippedAllowlist) {
+    // Note: logging happens in the caller (pi-tools/tools-invoke) after this function returns.
+    // We keep this note here for future maintainers.
+  }
   return {
     policy: strippedAllowlist ? { ...policy, allow: undefined } : policy,
     unknownAllowlist: Array.from(new Set(unknownAllowlist)),
diff --git a/src/gateway/tools-invoke-http.ts b/src/gateway/tools-invoke-http.ts
index 5fd525c8c..b747e2561 100644
--- a/src/gateway/tools-invoke-http.ts
+++ b/src/gateway/tools-invoke-http.ts
@@ -189,7 +189,7 @@ export async function handleToolsInvokeHttpRequest(
     if (resolved.unknownAllowlist.length > 0) {
       const entries = resolved.unknownAllowlist.join(", ");
       const suffix = resolved.strippedAllowlist
-        ? "Ignoring allowlist so core tools remain available."
+        ? "Ignoring allowlist so core tools remain available. Use tools.alsoAllow for additive plugin tool enablement."
         : "These entries won't match any tool unless the plugin is enabled.";
       logWarn(`tools: ${label} allowlist contains unknown entries (${entries}). ${suffix}`);
     }