diff --git a/crates/chat-cli/src/cli/chat/tools/custom_tool.rs b/crates/chat-cli/src/cli/chat/tools/custom_tool.rs
index 0e45205678..2a26c1c12b 100644
--- a/crates/chat-cli/src/cli/chat/tools/custom_tool.rs
+++ b/crates/chat-cli/src/cli/chat/tools/custom_tool.rs
@@ -44,6 +44,15 @@ impl Default for TransportType {
     }
 }
 
+#[derive(Clone, Serialize, Deserialize, Debug, Eq, PartialEq, JsonSchema)]
+#[serde(rename_all = "camelCase")]
+pub struct OAuthConfig {
+    /// Custom redirect URI for OAuth flow (e.g., "127.0.0.1:7778")
+    /// If not specified, a random available port will be assigned by the OS
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub redirect_uri: Option<String>,
+}
+
 #[derive(Clone, Serialize, Deserialize, Debug, Eq, PartialEq, JsonSchema)]
 #[serde(rename_all = "camelCase")]
 pub struct CustomToolConfig {
@@ -59,6 +68,9 @@ pub struct CustomToolConfig {
     /// Scopes with which oauth is done
     #[serde(default = "get_default_scopes")]
     pub oauth_scopes: Vec<String>,
+    /// OAuth configuration for this server
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub oauth: Option<OAuthConfig>,
     /// The command string used to initialize the mcp server
     #[serde(default)]
     pub command: String,
diff --git a/crates/chat-cli/src/mcp_client/client.rs b/crates/chat-cli/src/mcp_client/client.rs
index fefaa1a9cb..6598fc71db 100644
--- a/crates/chat-cli/src/mcp_client/client.rs
+++ b/crates/chat-cli/src/mcp_client/client.rs
@@ -453,11 +453,12 @@ impl McpClientService {
                     url,
                     headers,
                     oauth_scopes: scopes,
+                    oauth,
                     timeout,
                     ..
                 } = &self.config;
 
-                let http_service_builder = HttpServiceBuilder::new(url, os, url, *timeout, scopes, headers, messenger);
+                let http_service_builder = HttpServiceBuilder::new(url, os, url, *timeout, scopes, headers, oauth, messenger);
 
                 let (service, auth_client_wrapper) = http_service_builder.try_build(&self).await?;
 
diff --git a/crates/chat-cli/src/mcp_client/oauth_util.rs b/crates/chat-cli/src/mcp_client/oauth_util.rs
index dfd1e9e0e7..5a2199defe 100644
--- a/crates/chat-cli/src/mcp_client/oauth_util.rs
+++ b/crates/chat-cli/src/mcp_client/oauth_util.rs
@@ -196,6 +196,7 @@ pub struct HttpServiceBuilder<'a> {
     pub timeout: u64,
     pub scopes: &'a [String],
     pub headers: &'a HashMap<String, String>,
+    pub oauth_config: &'a Option<crate::cli::chat::tools::custom_tool::OAuthConfig>,
     pub messenger: &'a dyn Messenger,
 }
 
@@ -207,6 +208,7 @@ impl<'a> HttpServiceBuilder<'a> {
         timeout: u64,
         scopes: &'a [String],
         headers: &'a HashMap<String, String>,
+        oauth_config: &'a Option<crate::cli::chat::tools::custom_tool::OAuthConfig>,
         messenger: &'a dyn Messenger,
     ) -> Self {
         Self {
@@ -216,6 +218,7 @@ impl<'a> HttpServiceBuilder<'a> {
             timeout,
             scopes,
             headers,
+            oauth_config,
             messenger,
         }
     }
@@ -231,6 +234,7 @@ impl<'a> HttpServiceBuilder<'a> {
             timeout,
             scopes,
             headers,
+            oauth_config,
             messenger,
         } = self;
 
@@ -292,7 +296,9 @@ impl<'a> HttpServiceBuilder<'a> {
                                     cred_full_path.clone(),
                                     reg_full_path.clone(),
                                     scopes,
+                                    oauth_config,
                                     messenger,
+                                    os,
                                 )
                                 .await?;
 
@@ -452,7 +458,9 @@ async fn get_auth_manager(
     cred_full_path: PathBuf,
     reg_full_path: PathBuf,
     scopes: &[String],
+    oauth_config: &Option<crate::cli::chat::tools::custom_tool::OAuthConfig>,
     messenger: &dyn Messenger,
+    os: &Os,
 ) -> Result<AuthorizationManager, OauthUtilError> {
     let cred_as_bytes = tokio::fs::read(&cred_full_path).await;
     let reg_as_bytes = tokio::fs::read(&reg_full_path).await;
@@ -474,7 +482,7 @@ async fn get_auth_manager(
         _ => {
             info!("Error reading cached credentials");
             debug!("## mcp: cache read failed. constructing auth manager from scratch");
-            let (am, redirect_uri) = get_auth_manager_impl(oauth_state, scopes, messenger).await?;
+            let (am, redirect_uri) = get_auth_manager_impl(oauth_state, scopes, oauth_config, messenger, os).await?;
 
             // Client registration is done in [start_authorization]
             // If we have gotten past that point that means we have the info to persist the
@@ -509,9 +517,21 @@ async fn get_auth_manager(
 async fn get_auth_manager_impl(
     mut oauth_state: OAuthState,
     scopes: &[String],
+    oauth_config: &Option<crate::cli::chat::tools::custom_tool::OAuthConfig>,
     messenger: &dyn Messenger,
+    _os: &Os,
 ) -> Result<(AuthorizationManager, String), OauthUtilError> {
-    let socket_addr = SocketAddr::from(([127, 0, 0, 1], 0));
+    // Get port from per-server oauth config, or use 0 for random port assignment
+    let port = oauth_config
+        .as_ref()
+        .and_then(|cfg| cfg.redirect_uri.as_ref())
+        .and_then(|uri| {
+            // Parse port from redirect_uri like "127.0.0.1:7778" or ":7778"
+            uri.split(':').last().and_then(|p| p.parse::<u16>().ok())
+        })
+        .unwrap_or(0); // Port 0 = OS assigns random available port
+
+    let socket_addr = SocketAddr::from(([127, 0, 0, 1], port));
     let cancellation_token = tokio_util::sync::CancellationToken::new();
     let (tx, rx) = tokio::sync::oneshot::channel::<(String, String)>();
 
diff --git a/schemas/agent-v1.json b/schemas/agent-v1.json
index 5e72b08476..fb4c5e8964 100644
--- a/schemas/agent-v1.json
+++ b/schemas/agent-v1.json
@@ -94,6 +94,22 @@
               "offline_access"
             ]
           },
+          "oauth": {
+            "description": "OAuth configuration for this server",
+            "type": [
+              "object",
+              "null"
+            ],
+            "properties": {
+              "redirectUri": {
+                "description": "Custom redirect URI for OAuth flow (e.g., \"127.0.0.1:7778\"). If not specified, a random available port will be assigned by the OS",
+                "type": [
+                  "string",
+                  "null"
+                ]
+              }
+            }
+          },
           "command": {
             "description": "The command string used to initialize the mcp server",
             "type": "string",