From 82d89fd5fcfd4c6d28f9870fbfbd84874e7c97d1 Mon Sep 17 00:00:00 2001
From: MoerAI <skyinbss@gmail.com>
Date: Fri, 27 Mar 2026 11:11:56 +0900
Subject: [PATCH] fix(tools): add max_tools config to cap registered tools for
 OpenAI compatibility (fixes #2848)

---
 src/config/schema/experimental.ts |  2 ++
 src/plugin/tool-registry.ts       | 29 ++++++++++++++++++++++++++++-
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/src/config/schema/experimental.ts b/src/config/schema/experimental.ts
index 6abbf1a48..fbcefb3b1 100644
--- a/src/config/schema/experimental.ts
+++ b/src/config/schema/experimental.ts
@@ -21,6 +21,8 @@ export const ExperimentalConfigSchema = z.object({
   hashline_edit: z.boolean().optional(),
   /** Append fallback model info to session title when a runtime fallback occurs (default: false) */
   model_fallback_title: z.boolean().optional(),
+  /** Maximum number of tools to register. When set, lower-priority tools are excluded to stay within provider limits (e.g., OpenAI's 128-tool cap). Accounts for ~20 OpenCode built-in tools. */
+  max_tools: z.number().int().min(1).optional(),
 })
 
 export type ExperimentalConfig = z.infer<typeof ExperimentalConfigSchema>
diff --git a/src/plugin/tool-registry.ts b/src/plugin/tool-registry.ts
index 82a9a2ceb..556ee49e8 100644
--- a/src/plugin/tool-registry.ts
+++ b/src/plugin/tool-registry.ts
@@ -150,7 +150,34 @@ export function createToolRegistry(args: {
     normalizeToolArgSchemas(toolDefinition)
   }
 
-  const filteredTools = filterDisabledTools(allTools, pluginConfig.disabled_tools)
+  const filteredTools: ToolsRecord = filterDisabledTools(allTools, pluginConfig.disabled_tools)
+
+  const maxTools = pluginConfig.experimental?.max_tools
+  if (maxTools) {
+    const estimatedBuiltinTools = 20
+    const pluginToolBudget = maxTools - estimatedBuiltinTools
+    const toolEntries = Object.entries(filteredTools)
+    if (pluginToolBudget > 0 && toolEntries.length > pluginToolBudget) {
+      const excess = toolEntries.length - pluginToolBudget
+      log(`[tool-registry] Tool count (${toolEntries.length} plugin + ~${estimatedBuiltinTools} builtin = ~${toolEntries.length + estimatedBuiltinTools}) exceeds max_tools=${maxTools}. Trimming ${excess} lower-priority tools.`)
+      const lowPriorityTools = [
+        "session_list", "session_read", "session_search", "session_info",
+        "call_omo_agent", "interactive_bash", "look_at",
+        "task_create", "task_get", "task_list", "task_update",
+      ]
+      let removed = 0
+      for (const toolName of lowPriorityTools) {
+        if (removed >= excess) break
+        if (filteredTools[toolName]) {
+          delete filteredTools[toolName]
+          removed += 1
+        }
+      }
+      if (removed < excess) {
+        log(`[tool-registry] WARNING: Could not trim enough tools. ${toolEntries.length - removed} plugin tools remain.`)
+      }
+    }
+  }
 
   return {
     filteredTools,