Tool definitions don't accept valid special characters for function names or arguments, such as "ñ"

R functions that contain characters such as "ñ" (very common Spanish letter that produces a common problem in data science, as its used in the word _año_, meaning _year_) are completely valid in R, but they cause problems with `{ellmer}` Lets create a basic function that has `ñ` in its name and in its argument: ```r obtener_datos_por_año <- function(año = NULL) { require(dplyr) datos <- data.frame( año = c(2020, 2021, 2022, 2023, 2024), inversión = c(100, 150, 200, 250, 300), proyectos = c(5, 8, 12, 15, 18) ) datos <- datos |> filter(año == .env$año) return(datos) } ``` The function simply filters data from a dataframe. Try out the function and it will work fine: ```r obtener_datos_por_año(año = 2022) ``` Now let's create a tool definition with `{ellmer}`: ```r library(ellmer) # Crear la herramienta ellmer tool_obtener_datos <- ellmer::tool( obtener_datos_por_año, "Obtiene datos de inversión y proyectos, filtrados opcionalmente por año (2020-2024)", arguments = list( año = type_integer(description = "Año a filtrar, entre 2020 y 2024") ) ) ``` We get the first error: `ñ` is not supported in a function name: ``` # Error in `ellmer::tool()`: # ! `name` must contain only letters, numbers, - and _. ``` We have to change the function name (let´s say `anio` instead of `año`) to get rid of the error. Now let's provide the LLM with the function definition: ```r chat <- chat_anthropic( model = "claude-haiku-4-5" ) chat$register_tool(tool_obtener_datos) ``` No problem so far, but let's ask a question that requires the model to use the tool, specifically the argument with `ñ` in its name: ``` chat$chat("muéstrame los proyectos de 2020") # "show me projects from 2020" ``` We get another `ñ` related error: ``` # Error in `req_perform_connection()`: # ! HTTP 400 Bad Request. # ℹ tools.0.custom.input_schema.properties: Property keys should match # pattern '^[a-zA-Z0-9_.-]{1,64}$' [invalid_request_error] # Run `rlang::last_trace()` to see where the error occurred. ``` I believe some cautions were taken to validate proper function and argument names in `{ellmer}` but those leave some users having to modify their work in order to match the english alphabet.