Allow RubyLLM::Schema to be used for Tool schema (OpenAI, Anthropic and Gemini)

[bricolage]

What this does

A modest attempt to use RubyLLM::Schema with tools. Just for OpenAI and Anthropic as proof-of-concept.

I understand this is being worked on (see refs below), I thought I'd submit this for feedback on the interface. I use this in my own app.

class TodosSchema < RubyLLM::Schema
      array :todos do
      object do
        string :content, description: 'Todo to track'
        string :status, enum: %w[pending in_progress completed]
      end
    end
end

class TodosTool < RubyLLM::Tool
  schema TodosSchema
  # ...
end

I have not worked through validation issues (e.g. if neither param nor schema is called in the tool class. Currently it returns {}

Type of change

• Bug fix
• New feature
• Breaking change
• Documentation
• Performance improvement

Scope check

• I read the Contributing Guide
• This aligns with RubyLLM's focus on LLM communication
• This isn't application-specific logic that belongs in user code
• This benefits most users, not just my specific use case

Quality check

• I ran overcommit --install and all hooks pass
• I tested my changes thoroughly
• I updated documentation if needed
• I didn't modify auto-generated files manually (models.json, aliases.json)

API changes

• Breaking change
• New public methods/classes
• Changed method signatures
• No API changes

Related issues

#76
#11 (comment)
#332 (comment)

[tpaulshippy]

Nice! What is missing, provider wise? Gemini?

[tpaulshippy]

Looks pretty straightforward to me. Feels like if we get Gemini added this should be good to go.

[bricolage]

@tpaulshippy all set, should be gtg

[bricolage]

@tpaulshippy I added some docs, take a look at those if you can

[tpaulshippy]

The only thing I'm noticing that I expect @crmne might ask for is at least one spec that hits the real APIs (with VCR cassettes).

[crmne]

Hey @bricolage thanks for your effort on this PR. I'm not sure if it's the direction I want to go into for complex parameters for Tools as it may be a bit confusing to define a schema externally from the Tool, and then using it in the tool.

I feel like in a tool we should have params instead. Before you both put a ton of effort on this, let me think about it and come up with a good design.

[bricolage]

Yeah no problem, this was just my own drop-in solution, I understood it might not be idiomatic. If I can help further let me know!

[bricolage]

So you are thinking of just letting param take a block and do a light mapping to an internal RubyLLM::Schema? That's nice and simple. And is similar to what langchain.rb does: https://github.com/patterns-ai-core/langchainrb/blob/main/lib/langchain/tool_definition.rb

class TodosTool < RubyLLM::Tool
  param :todos, type: :array, desc: 'List of todos', required: true do
    param :content, description: 'Todo to track'
    param :status
  end
end