diff --git a/crates/goose/src/agents/capabilities.rs b/crates/goose/src/agents/capabilities.rs
index da6cb4029c..9e625e00d6 100644
--- a/crates/goose/src/agents/capabilities.rs
+++ b/crates/goose/src/agents/capabilities.rs
@@ -19,6 +19,20 @@ pub struct Capabilities {
     provider_usage: Mutex<Vec<ProviderUsage>>,
 }
 
+/// Sanitizes a string by replacing invalid characters with underscores.
+/// Valid characters match [a-zA-Z0-9_-]
+fn sanitize(input: String) -> String {
+    let mut result = String::with_capacity(input.len());
+    for c in input.chars() {
+        result.push(if c.is_ascii_alphanumeric() || c == '_' || c == '-' {
+            c
+        } else {
+            '_'
+        });
+    }
+    result
+}
+
 impl Capabilities {
     /// Create a new Capabilities with the specified provider
     pub fn new(provider: Box<dyn Provider>) -> Self {
@@ -64,7 +78,7 @@ impl Capabilities {
 
         // Store the client
         self.clients.insert(
-            init_result.server_info.name.clone(),
+            sanitize(init_result.server_info.name.clone()),
             Arc::new(Mutex::new(client)),
         );