From 5d43ea69add422ac6259a8be549e6ebeafd86cc4 Mon Sep 17 00:00:00 2001
From: centdix <farhadg110@gmail.com>
Date: Sun, 28 Sep 2025 13:08:51 +0000
Subject: [PATCH] filter out tools with too long names

---
 backend/windmill-api/src/mcp/server.rs        | 75 +++++++++++--------
 .../components/settings/CreateToken.svelte    | 26 ++++++-
 2 files changed, 64 insertions(+), 37 deletions(-)

diff --git a/backend/windmill-api/src/mcp/server.rs b/backend/windmill-api/src/mcp/server.rs
index fa8644b5b8..fffbc8fa5b 100644
--- a/backend/windmill-api/src/mcp/server.rs
+++ b/backend/windmill-api/src/mcp/server.rs
@@ -50,6 +50,9 @@ use rmcp::transport::streamable_http_server::{
 };
 use windmill_common::error::JsonResult;
 
+// MCP clients do not allow names longer than 60 characters
+const MAX_PATH_LENGTH: usize = 60;
+
 /// MCP Server Runner - implements the core MCP protocol handlers
 #[derive(Clone)]
 pub struct Runner {}
@@ -381,45 +384,51 @@ impl ServerHandler for Runner {
         let mut tools: Vec<Tool> = Vec::new();
 
         for script in scripts {
-            tools.push(
-                Runner::create_tool_from_item(
-                    &script,
-                    user_db,
-                    authed,
-                    &workspace_id,
-                    &mut resources_cache,
-                    &resources_types,
-                )
-                .await?,
-            );
+            if script.get_path_or_id().len() <= MAX_PATH_LENGTH {
+                tools.push(
+                    Runner::create_tool_from_item(
+                        &script,
+                        user_db,
+                        authed,
+                        &workspace_id,
+                        &mut resources_cache,
+                        &resources_types,
+                    )
+                    .await?,
+                );
+            }
         }
 
         for flow in flows {
-            tools.push(
-                Runner::create_tool_from_item(
-                    &flow,
-                    user_db,
-                    authed,
-                    &workspace_id,
-                    &mut resources_cache,
-                    &resources_types,
-                )
-                .await?,
-            );
+            if flow.get_path_or_id().len() <= MAX_PATH_LENGTH {
+                tools.push(
+                    Runner::create_tool_from_item(
+                        &flow,
+                        user_db,
+                        authed,
+                        &workspace_id,
+                        &mut resources_cache,
+                        &resources_types,
+                    )
+                    .await?,
+                );
+            }
         }
 
         for hub_script in hub_scripts {
-            tools.push(
-                Runner::create_tool_from_item(
-                    &hub_script,
-                    user_db,
-                    authed,
-                    &workspace_id,
-                    &mut resources_cache,
-                    &resources_types,
-                )
-                .await?,
-            );
+            if hub_script.get_path_or_id().len() <= MAX_PATH_LENGTH {
+                tools.push(
+                    Runner::create_tool_from_item(
+                        &hub_script,
+                        user_db,
+                        authed,
+                        &workspace_id,
+                        &mut resources_cache,
+                        &resources_types,
+                    )
+                    .await?,
+                );
+            }
         }
 
         // Add endpoint tools from the generated MCP tools
diff --git a/frontend/src/lib/components/settings/CreateToken.svelte b/frontend/src/lib/components/settings/CreateToken.svelte
index 18341375ed..e1d93dcf40 100644
--- a/frontend/src/lib/components/settings/CreateToken.svelte
+++ b/frontend/src/lib/components/settings/CreateToken.svelte
@@ -39,6 +39,8 @@
 		newTokenLabel = $bindable(undefined)
 	}: Props = $props()
 
+	const MAX_PATH_LENGTH = 55
+
 	let newToken = $state<string | undefined>(undefined)
 	let newMcpToken = $state<string | undefined>(undefined)
 	let newTokenExpiration = $state<number | undefined>(undefined)
@@ -124,6 +126,17 @@
 			: 'Create your first scripts or flows to make them available via MCP.'
 	)
 	const noScriptsOrFlowsAvailableWarning = $derived(includedRunnables.length === 0 ? warning : '')
+	const longPathRunnables = $derived(
+		includedRunnables.filter((path) => path.length > MAX_PATH_LENGTH)
+	)
+	const validRunnables = $derived(
+		includedRunnables.filter((path) => path.length <= MAX_PATH_LENGTH)
+	)
+	const longPathWarning = $derived(
+		longPathRunnables.length > 0
+			? `${longPathRunnables.length} script(s)/flow(s) have paths longer than 60 characters and will be excluded from MCP tools. Consider shortening the paths: ${longPathRunnables.slice(0, 3).join(', ')}${longPathRunnables.length > 3 ? ` and ${longPathRunnables.length - 3} more` : ''}`
+			: ''
+	)
 
 	$effect(() => {
 		if (mcpCreationMode) {
@@ -406,20 +419,25 @@
 								{noScriptsOrFlowsAvailableWarning}
 							</Alert>
 						{:else}
+							{#if longPathWarning}
+								<Alert type="warning" title="Some paths are too long" size="xs">
+									{longPathWarning}
+								</Alert>
+							{/if}
 							<span class="block text-xs text-tertiary"
 								>Scripts & Flows that will be available via MCP</span
 							>
 							<div class="flex flex-wrap gap-1">
-								{#if includedRunnables.length <= 5}
-									{#each includedRunnables as scriptOrFlow}
+								{#if validRunnables.length <= 5}
+									{#each validRunnables as scriptOrFlow}
 										<Badge rounded small color="blue">{scriptOrFlow}</Badge>
 									{/each}
 								{:else}
-									{#each includedRunnables.slice(0, 3) as scriptOrFlow}
+									{#each validRunnables.slice(0, 3) as scriptOrFlow}
 										<Badge rounded small color="blue">{scriptOrFlow}</Badge>
 									{/each}
 									<Badge rounded small color="dark-gray">
-										+{includedRunnables.length - 3} more
+										+{validRunnables.length - 3} more
 									</Badge>
 								{/if}
 							</div>