diff --git a/astrbot/core/agent/tool.py b/astrbot/core/agent/tool.py
index aba421f3d..42b7e8eb4 100644
--- a/astrbot/core/agent/tool.py
+++ b/astrbot/core/agent/tool.py
@@ -106,6 +106,15 @@ class ToolSet:
         """Remove a tool by its name."""
         self.tools = [tool for tool in self.tools if tool.name != name]
 
+    def normalize(self) -> None:
+        """Sort tools by name for deterministic serialization.
+
+        This ensures the serialized tool schema sent to the LLM is
+        identical across requests regardless of registration/injection
+        order, enabling LLM provider prefix cache hits.
+        """
+        self.tools.sort(key=lambda t: t.name)
+
     def get_tool(self, name: str) -> FunctionTool | None:
         """Get a tool by its name."""
         for tool in self.tools:
diff --git a/astrbot/core/astr_agent_tool_exec.py b/astrbot/core/astr_agent_tool_exec.py
index 27d6aeae3..8b9bcf0c2 100644
--- a/astrbot/core/astr_agent_tool_exec.py
+++ b/astrbot/core/astr_agent_tool_exec.py
@@ -169,10 +169,61 @@ class FunctionToolExecutor(BaseFunctionToolExecutor[AstrAgentContext]):
 
             return
         else:
+            # Guard: reject sandbox tools whose capability is unavailable.
+            # Tools are always injected (for schema stability / prefix caching),
+            # but execution is blocked when the sandbox lacks the capability.
+            rejection = cls._check_sandbox_capability(tool, run_context)
+            if rejection is not None:
+                yield rejection
+                return
+
             async for r in cls._execute_local(tool, run_context, **tool_args):
                 yield r
             return
 
+    # Browser tool names that require the "browser" sandbox capability.
+    _BROWSER_TOOL_NAMES: frozenset[str] = frozenset({
+        "astrbot_execute_browser",
+        "astrbot_execute_browser_batch",
+        "astrbot_run_browser_skill",
+    })
+
+    @classmethod
+    def _check_sandbox_capability(
+        cls,
+        tool: FunctionTool,
+        run_context: ContextWrapper[AstrAgentContext],
+    ) -> mcp.types.CallToolResult | None:
+        """Return a rejection result if the tool requires a sandbox capability
+        that is not available, or None if the tool may proceed."""
+        if tool.name not in cls._BROWSER_TOOL_NAMES:
+            return None
+
+        from astrbot.core.computer.computer_client import get_sandbox_capabilities
+
+        session_id = run_context.context.event.unified_msg_origin
+        caps = get_sandbox_capabilities(session_id)
+
+        # Sandbox not yet booted — allow through (boot will happen on first
+        # shell/python call; browser tools will fail naturally if truly unavailable).
+        if caps is None:
+            return None
+
+        if "browser" not in caps:
+            msg = (
+                f"Tool '{tool.name}' requires browser capability, but the current "
+                f"sandbox profile does not include it (capabilities: {list(caps)}). "
+                "Please ask the administrator to switch to a sandbox profile with "
+                "browser support, or use shell/python tools instead."
+            )
+            logger.warning("[ToolExec] capability_rejected tool=%s caps=%s", tool.name, list(caps))
+            return mcp.types.CallToolResult(
+                content=[mcp.types.TextContent(type="text", text=msg)],
+                isError=True,
+            )
+
+        return None
+
     @classmethod
     def _get_runtime_computer_tools(
         cls,
diff --git a/astrbot/core/astr_main_agent.py b/astrbot/core/astr_main_agent.py
index f65fb9919..dedd58574 100644
--- a/astrbot/core/astr_main_agent.py
+++ b/astrbot/core/astr_main_agent.py
@@ -1074,6 +1074,10 @@ async def build_main_agent(
         asyncio.create_task(_handle_webchat(event, req, provider))
 
     if req.func_tool and req.func_tool.tools:
+        # Sort tools by name for deterministic serialization so that
+        # LLM provider prefix caching can match across requests.
+        req.func_tool.normalize()
+
         tool_prompt = (
             TOOL_CALL_PROMPT
             if config.tool_schema_mode == "full"
diff --git a/astrbot/core/computer/computer_tool_provider.py b/astrbot/core/computer/computer_tool_provider.py
index 998cb11f8..7a2952dc5 100644
--- a/astrbot/core/computer/computer_tool_provider.py
+++ b/astrbot/core/computer/computer_tool_provider.py
@@ -181,15 +181,17 @@ class ComputerToolProvider:
     def _sandbox_tools(self, ctx: ToolProviderContext) -> list[FunctionTool]:
         """Collect tools for sandbox mode.
 
-        Prefers the precise post-boot tool list from the running session's
-        booter instance (``get_sandbox_tools``).  When the sandbox has not
-        yet been booted, falls back to the conservative pre-boot default
-        declared by the booter class (``get_default_sandbox_tools``).
+        Always returns the full (pre-boot default) tool set declared by the
+        booter class, regardless of whether the sandbox is already booted.
+
+        This ensures the tool schema sent to the LLM is stable across the
+        entire conversation lifecycle (pre-boot and post-boot produce the
+        same set), enabling LLM prefix cache hits.  Tools whose underlying
+        capability is unavailable at runtime are rejected by the executor
+        with a descriptive error message instead of being omitted from the
+        schema.
         """
-        from astrbot.core.computer.computer_client import (
-            get_default_sandbox_tools,
-            get_sandbox_tools,
-        )
+        from astrbot.core.computer.computer_client import get_default_sandbox_tools
 
         booter_type = ctx.sandbox_cfg.get("booter", "shipyard_neo")
 
@@ -203,12 +205,7 @@ class ComputerToolProvider:
             os.environ["SHIPYARD_ENDPOINT"] = ep
             os.environ["SHIPYARD_ACCESS_TOKEN"] = at
 
-        # Prefer precise post-boot tools from the running session
-        booted_tools = get_sandbox_tools(ctx.session_id)
-        if booted_tools:
-            return booted_tools
-
-        # Pre-boot: conservative default from booter class
+        # Always return the full tool set for schema stability
         return get_default_sandbox_tools(ctx.sandbox_cfg)
 
     def _sandbox_prompt_addon(self, ctx: ToolProviderContext) -> str: