support arbitrary ellmer tools

[simonpcouch]

So far, acquaint has only supported tools from btw. This PR allows users to register any other ellmer tools they'd like to be able to run in their R session.

This could be e.g.

• A general execute_r_code() tool, for the brave
• A suite of tools specifically aimed at R package development, presumably hooked up to something like Claude Code or Codex

Here's an example chat where I've registered rnorm as a tool using the following in my .Rprofile:

tool_rnorm <- ellmer::tool(
  stats::rnorm,
  "Draw numbers from a random normal distribution",
  n = ellmer::type_integer(
    "The number of observations. Must be a positive integer."
  ),
  mean = ellmer::type_number("The mean value of the distribution."),
  sd = ellmer::type_number(
    "The standard deviation of the distribution. Must be a non-negative number."
  ),
  .name = "random_normal"
)

acquaint::set_acquaint_tools(list(tool_rnorm))

[shikokuchuo]

So, naming... if we expect the call (usually) to be namespaced, would the repetition of 'acquaint' be a bit verbose? Would mcp_set_tools() make sense? Just a thought - whatever you decide is fine.

[simonpcouch]

Yeah, good point.

• set_tools() feels a bit aggressive, e.g. might name-conflict with too many things
• mcp_tools() is maybe okay and fits in with the naming pattern nicely, but ambiguous whether it gets or sets the tools?
• set_mcp_tools() is almost as long as set_acquaint_tools().

Thoughts?

[simonpcouch]

Oh, didn't see you had updated your comment—I think mcp_set_tools() is reasonable!