This change makes the `tool` macro's output safe for the `missing_docs` lint, by
emitting a doc comment for the generated `[tool]_tool_attr` function. This doc
comment is emitted regardless of whether the tool function is public, for simplicity.
We are building an MCP server using `rmcp` and discovered that the current crate
was not compatible with the `#![deny(missing_docs)]` lint which we use everywhere.
Tested by modifying the `test_tool_macros.rs` test to use `#![deny(missing_docs)]`
and adding doc comments to all pub fns and structs in that file.
None.
Fixes#438.
Co-authored-by: RobJellinghaus <rjellinghaus@live.com>