[Docs] Use ToolCallException in the first tool example and add builder defaults

docs/run/server-builder.md

@@ -114,16 +114,20 @@ use Mcp\Server\Wire\CachePolicy;
 $server = Server::builder()
     // Signs the state a multi round-trip request carries through the client.
     // The same key must reach every process that might serve the retry.
+    // The key needs at least 32 bytes, otherwise build() throws. TTL in seconds, default 600.
+    // Without a key, the server refuses every state the client sends back.
     ->setRequestState($_ENV['MCP_REQUEST_STATE_KEY'], ttl: 600)
 
     // Bounds the input-required shim, which fulfils an `InputRequiredResult`
     // over a handshake-era connection. `withoutInputRequiredShim()` turns it off.
+    // Defaults to 8 rounds and a 600 second timeout for each input request.
     ->setInputRequiredLimits(maxRounds: 4, roundTimeout: 120)
 
     // Caching hints stamped on cacheable results. Defaults to `ttlMs: 0, private`.
     ->setCachePolicy(CachePolicy::default(30_000)->withMethod('tools/list', 3_600_000, CacheScope::Public))
 
     // Delivery for `subscriptions/listen`, and how long such a stream is held.
+    // The lifetime defaults to 30 seconds; 0 keeps the stream open until the client or the runtime ends it.
     ->setNotificationBus(new Psr16NotificationBus($cache))
     ->setSubscriptionLifetime(0)
 

docs/servers/tools.md

@@ -4,6 +4,7 @@ Tools are callable functions that perform actions and return results.
 
 ```php
 use Mcp\Capability\Attribute\McpTool;
+use Mcp\Exception\ToolCallException;
 
 class Calculator
 {
@@ -17,8 +18,8 @@ class Calculator
             'add' => $a + $b,
             'subtract' => $a - $b,
             'multiply' => $a * $b,
-            'divide' => $b != 0 ? $a / $b : throw new \InvalidArgumentException('Division by zero'),
-            default => throw new \InvalidArgumentException('Invalid operation')
+            'divide' => $b != 0 ? $a / $b : throw new ToolCallException('Division by zero'),
+            default => throw new ToolCallException('Invalid operation')
         };
     }
 }