Add eval for open_tool (#29801)

Also have its description say it should only be used on request

Release Notes:

- N/A

crates/eval/src/examples/mod.rs

@@ -14,12 +14,14 @@ use crate::example::{Example, ExampleContext, ExampleMetadata, JudgeAssertion};
 mod add_arg_to_trait_method;
 mod code_block_citations;
 mod file_search;
+mod planets;
 
 pub fn all(examples_dir: &Path) -> Vec<Rc<dyn Example>> {
     let mut threads: Vec<Rc<dyn Example>> = vec![
         Rc::new(file_search::FileSearchExample),
         Rc::new(add_arg_to_trait_method::AddArgToTraitMethod),
         Rc::new(code_block_citations::CodeBlockCitations),
+        Rc::new(planets::Planets),
     ];
 
     for example_path in list_declarative_examples(examples_dir).unwrap() {