diff --git a/packages/opencode/src/tool/shell.ts b/packages/opencode/src/tool/shell.ts
index d3ca542684de..a9df8bb6454a 100644
--- a/packages/opencode/src/tool/shell.ts
+++ b/packages/opencode/src/tool/shell.ts
@@ -620,7 +620,7 @@ export const ShellTool = Tool.define(
                   cwd,
                   env: yield* shellEnv(ctx, cwd),
                   timeout,
-                  description: params.description,
+                  description: params.description ?? "",
                 },
                 ctx,
               )
diff --git a/packages/opencode/src/tool/shell/prompt.ts b/packages/opencode/src/tool/shell/prompt.ts
index 45c637863a6b..0a5fce8f9ce0 100644
--- a/packages/opencode/src/tool/shell/prompt.ts
+++ b/packages/opencode/src/tool/shell/prompt.ts
@@ -26,7 +26,7 @@ export function parameterSchema(description: string) {
     workdir: Schema.optional(Schema.String).annotate({
       description: `The working directory to run the command in. Defaults to the current directory. Use this instead of 'cd' commands.`,
     }),
-    description: Schema.String.annotate({ description }),
+    description: Schema.optional(Schema.String).annotate({ description }),
   })
 }