diff --git a/packages/opencode/src/session/prompt.ts b/packages/opencode/src/session/prompt.ts
index f403ef22..32c72e23 100644
--- a/packages/opencode/src/session/prompt.ts
+++ b/packages/opencode/src/session/prompt.ts
@@ -533,6 +533,7 @@ export namespace SessionPrompt {
               args,
             },
           )
+          item.parameters.parse(args)
           const result = await item.execute(args, {
             sessionID: input.sessionID,
             abort: options.abortSignal!,