Class: LLM::Agent

Inherits:
Object
  • Object
show all
Defined in:
lib/llm/agent.rb

Overview

LLM::Agent provides a class-level DSL for defining reusable, preconfigured assistants with defaults for model, tools, schema, and instructions.

It wraps the same stateful runtime surface as LLM::Context: message history, usage, persistence, streaming parameters, and provider-backed requests still flow through an underlying context. The defining behavior of an agent is that it automatically resolves pending tool calls for you during talk and respond, instead of leaving tool loops to the caller.

Notes:

  • Instructions are injected once unless a system message is already present.
  • An agent automatically executes tool loops (unlike LLM::Context).
  • The automatic tool loop enables the wrapped context's guard by default. The built-in LLM::LoopGuard detects repeated tool-call patterns and blocks stuck execution before more tool work is queued.
  • The default tool attempt budget is 25. After that, the agent sends advisory tool errors back through the model and keeps the loop in-band. Set tool_attempts: nil to disable that advisory behavior.
  • Tool loop execution can be configured with concurrency :call, :thread, :task, :fiber, or :ractor.

Examples:

class SystemAdmin < LLM::Agent
  model "gpt-4.1-nano"
  instructions "You are a Linux system admin"
  tools Shell
  schema Result
end

llm = LLM.openai(key: ENV["KEY"])
agent = SystemAdmin.new(llm)
agent.talk("Run 'date'")

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(llm, params = {}) ⇒ Agent

Returns a new instance of Agent.

Parameters:

  • provider (LLM::Provider) —

    A provider

  • params (Hash) (defaults to: {}) —

    The parameters to maintain throughout the conversation. Any parameter the provider supports can be included and not only those listed here.

Options Hash (params):

  • :model (String) —

    Defaults to the provider's default model

  • :tools (Array<LLM::Function>, nil) —

    Defaults to nil

  • :skills (Array<String>, nil) —

    Defaults to nil

  • :schema (#to_json, nil) —

    Defaults to nil

  • :stream (Object, Proc, nil) —

    Optional stream override for this agent instance

  • :tracer (LLM::Tracer, Proc, nil) —

    Optional tracer override for this agent instance

  • :concurrency (Symbol, Array<Symbol>, nil) —

    Defaults to the agent class concurrency



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# File 'lib/llm/agent.rb', line 187

def initialize(llm, params = {})
  @llm = llm
  fields = %i[model skills schema tracer stream tools concurrency instructions confirm]
  fields_ivar = %i[tracer concurrency instructions confirm]
  fields.each do |field|
    resolvable = params.key?(field) ? params.delete(field) : self.class.public_send(field)
    resolve_symbol = !%i[concurrency confirm].include?(field)
    resolved = resolvable != nil ? resolve_option(self, resolvable, resolve_symbol:) : resolvable
    resolved = [*resolved].map(&:to_s) if field == :confirm && resolved
    if field == :model
      params[field] = resolved unless resolved.nil? || params.key?(field)
    elsif resolved && !fields_ivar.include?(field)
      params[field] ||= resolved
    elsif fields_ivar.include?(field)
      instance_variable_set(:"@#{field}", resolved)
    end
  end
  @ctx = LLM::Context.new(llm, {guard: true}.merge(params))
end

Instance Attribute Details

#llm ⇒ LLM::Provider (readonly)

Returns a provider

Returns:



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# File 'lib/llm/agent.rb', line 43

def llm
  @llm
end

Class Method Details

.tools(*tools, &block) ⇒ Array<LLM::Function>

Set or get the default tools

Parameters:

Returns:

  • (Array<LLM::Function>) —

    Returns the current tools when no argument is provided



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# File 'lib/llm/agent.rb', line 62

def self.tools(*tools, &block)
  return @tools || [] if tools.empty? && !block
  @tools = block || tools.flatten
end

.skills(*skills, &block) ⇒ Array<String>?

Set or get the default skills

Parameters:

  • skills (Array<String>, nil) —

    One or more skill directories

Returns:

  • (Array<String>, nil) —

    Returns the current skills when no argument is provided



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# File 'lib/llm/agent.rb', line 73

def self.skills(*skills, &block)
  return @skills if skills.empty? && !block
  @skills = block || skills.flatten
end

.schema(schema = nil, &block) ⇒ #to_json?

Set or get the default schema

Parameters:

  • schema (#to_json, nil) (defaults to: nil) —

    The schema

Returns:

  • (#to_json, nil) —

    Returns the current schema when no argument is provided



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# File 'lib/llm/agent.rb', line 84

def self.schema(schema = nil, &block)
  return @schema if schema.nil? && !block
  @schema = block || schema
end

.instructions(instructions = nil) ⇒ String?

Set or get the default instructions

Parameters:

  • instructions (String, nil) (defaults to: nil) —

    The system instructions

Returns:

  • (String, nil) —

    Returns the current instructions when no argument is provided



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# File 'lib/llm/agent.rb', line 95

def self.instructions(instructions = nil)
  return @instructions if instructions.nil?
  @instructions = instructions
end

.concurrency(concurrency = nil) ⇒ Symbol, ...

Set or get the tool execution concurrency.

Parameters:

  • concurrency (Symbol, Array<Symbol>, nil) (defaults to: nil) —

    Controls how pending tool loops are executed:

    • :call: sequential calls
    • :thread: concurrent threads
    • :task: concurrent async tasks
    • :fiber: concurrent scheduler-backed fibers
    • :fork: forked child processes
    • :ractor: concurrent Ruby ractors for class-based tools; MCP tools are not supported, and this mode is especially useful for CPU-bound tool work Usually pass a single strategy. Arrays are only for advanced mixed-work cases and are not needed for normal queued stream tool loops.

Returns:

  • (Symbol, Array<Symbol>, nil) 


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# File 'lib/llm/agent.rb', line 115

def self.concurrency(concurrency = nil)
  return @concurrency if concurrency.nil?
  @concurrency = concurrency
end

.tracer(tracer = nil, &block) ⇒ LLM::Tracer, ...

Set or get the default tracer.

When a block is provided, it is stored and evaluated lazily against the agent instance during initialization so it can build a tracer from the resolved provider.

Examples:

class Agent < LLM::Agent
  tracer { LLM::Tracer::Logger.new(llm, io: $stdout) }
end

Parameters:

Yield Returns:

Returns:



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# File 'lib/llm/agent.rb', line 135

def self.tracer(tracer = nil, &block)
  return @tracer if tracer.nil? && !block
  @tracer = block || tracer
end

.stream(stream = nil, &block) ⇒ Object, ...

Set or get the default stream.

When a block is provided, it is stored and evaluated lazily against the agent instance during initialization so it can build a fresh stream for each agent.

Examples:

class Agent < LLM::Agent
  stream { MyStream.new }
end

Parameters:

  • stream (Object, Proc, nil) (defaults to: nil)

Yield Returns:

Returns:



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# File 'lib/llm/agent.rb', line 155

def self.stream(stream = nil, &block)
  return @stream if stream.nil? && !block
  @stream = block || stream
end

.confirm(*tool_names, &block) ⇒ Array<String>, ...

Set or get the tool names that require confirmation before they can run.

Parameters:

  • tool_names (String, Symbol, Array<String, Symbol>, Proc) —

    One or more tool names.

  • block (Proc) —

    An optional, lazy-evaluated Proc

Returns:

  • (Array<String>, Proc, nil) 


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# File 'lib/llm/agent.rb', line 168

def self.confirm(*tool_names, &block)
  return @confirm if tool_names.empty? && !block
  @confirm = block || tool_names.flatten.map(&:to_s)
end

.model(model = nil, &block) ⇒ String?

Set or get the default model

Parameters:

  • model (String, nil) (defaults to: nil) —

    The model identifier

Returns:

  • (String, nil) —

    Returns the current model when no argument is provided



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# File 'lib/llm/agent.rb', line 51

def self.model(model = nil, &block)
  return @model if model.nil? && !block
  @model = block || model
end

Instance Method Details

#on_tool_confirmation(fn, strategy) ⇒ LLM::Function::Return

This method is called when confirmation is required before a tool can run.

Parameters:

  • fn (LLM::Function) —

    The pending function call. It can be cancelled through the Function#cancel method.

  • strategy (Symbol, Array<Symbol>) —

    The execution strategy that would be used for the tool call.

Returns:

  • (LLM::Function::Return) —

    Return either fn.spawn(strategy).wait to approve execution or fn.cancel(...) to cancel the call.



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# File 'lib/llm/agent.rb', line 411

def on_tool_confirmation(fn, strategy)
  fn.cancel
end

#talk(prompt, params = {}) ⇒ LLM::Response

Maintain a conversation via the chat completions API. This method immediately sends a request to the LLM and returns the response.

Examples:

llm = LLM.openai(key: ENV["KEY"])
agent = LLM::Agent.new(llm)
response = agent.talk("Hello, what is your name?")
puts response.choices[0].content

Parameters:

  • params (Hash) (defaults to: {}) —

    The params passed to the provider, including optional :stream, :tools, :schema etc.

  • prompt (String) —

    The input prompt to be completed

Options Hash (params):

  • :tool_attempts (Integer) —

    The maxinum number of tool call iterations before the agent sends in-band advisory tool errors back through the model (default 25). Set to nil to disable advisory tool-limit returns.

Returns:



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# File 'lib/llm/agent.rb', line 223

def talk(prompt, params = {})
  run_loop(prompt, params, :talk)
end

#ask(prompt, params = {}) ⇒ Object

See Also:



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# File 'lib/llm/agent.rb', line 229

def ask(prompt, params = {})
  run_loop(prompt, params, :ask)
end

#messages ⇒ LLM::Buffer<LLM::Message>

Returns:



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# File 'lib/llm/agent.rb', line 235

def messages
  @ctx.messages
end

#functions ⇒ Array<LLM::Function>

Returns:



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# File 'lib/llm/agent.rb', line 241

def functions
  @tracer ? @llm.with_tracer(@tracer) { @ctx.functions } : @ctx.functions
end

#returns ⇒ Array<LLM::Function::Return>

Returns:

See Also:



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# File 'lib/llm/agent.rb', line 248

def returns
  @ctx.returns
end

#wait ⇒ Array<LLM::Function::Return>

Returns:

See Also:



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# File 'lib/llm/agent.rb', line 255

def wait(...)
  @tracer ? @llm.with_tracer(@tracer) { @ctx.wait(...) } : @ctx.wait(...)
end

#usage ⇒ LLM::Object

Returns:



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# File 'lib/llm/agent.rb', line 261

def usage
  @ctx.usage
end

#interrupt! ⇒ nil Also known as: cancel!

Interrupt the active request, if any.

Returns:

  • (nil) 


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# File 'lib/llm/agent.rb', line 268

def interrupt!
  @ctx.interrupt!
end

#prompt(&b) ⇒ LLM::Prompt Also known as: build_prompt

Parameters:

  • b (Proc) —

    A block that composes messages. If it takes one argument, it receives the prompt object. Otherwise it runs in prompt context.

Returns:

See Also:



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# File 'lib/llm/agent.rb', line 277

def prompt(&b)
  @ctx.prompt(&b)
end

#image_url(url) ⇒ LLM::Object

Returns a tagged object

Parameters:

  • url (String) —

    The URL

Returns:



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# File 'lib/llm/agent.rb', line 287

def image_url(url)
  @ctx.image_url(url)
end

#local_file(path) ⇒ LLM::Object

Returns a tagged object

Parameters:

  • path (String) —

    The path

Returns:



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# File 'lib/llm/agent.rb', line 296

def local_file(path)
  @ctx.local_file(path)
end

#remote_file(res) ⇒ LLM::Object

Returns a tagged object

Parameters:

Returns:



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# File 'lib/llm/agent.rb', line 305

def remote_file(res)
  @ctx.remote_file(res)
end

#tracer ⇒ LLM::Tracer

Returns an LLM tracer

Returns:



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# File 'lib/llm/agent.rb', line 312

def tracer
  @tracer || @ctx.tracer
end

#stream ⇒ LLM::Stream, ...

Returns a stream object, or nil

Returns:

  • (LLM::Stream, #<<, nil) —

    Returns a stream object, or nil



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# File 'lib/llm/agent.rb', line 319

def stream
  @ctx.stream
end

#model ⇒ String

Returns the model an Agent is actively using

Returns:

  • (String) 


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# File 'lib/llm/agent.rb', line 326

def model
  @ctx.model
end

#mode ⇒ Symbol

Returns:

  • (Symbol) 


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# File 'lib/llm/agent.rb', line 332

def mode
  @ctx.mode
end

#concurrency ⇒ Symbol, ...

Returns the configured tool execution concurrency.

Returns:

  • (Symbol, Array<Symbol>, nil) 


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# File 'lib/llm/agent.rb', line 339

def concurrency
  @concurrency
end

#cost ⇒ LLM::Cost

Returns:

See Also:



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# File 'lib/llm/agent.rb', line 346

def cost
  @ctx.cost
end

#context_window ⇒ Integer

Returns:

  • (Integer)

See Also:



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# File 'lib/llm/agent.rb', line 353

def context_window
  @ctx.context_window
end

#params ⇒ Hash

Returns:

  • (Hash)

See Also:



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# File 'lib/llm/agent.rb', line 360

def params
  @ctx.params
end

#to_h ⇒ Hash

Returns:

  • (Hash)

See Also:



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# File 'lib/llm/agent.rb', line 367

def to_h
  @ctx.to_h
end

#to_json ⇒ String

Returns:

  • (String) 


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# File 'lib/llm/agent.rb', line 373

def to_json(...)
  LLM.json.dump(to_h, ...)
end

#inspect ⇒ String

Returns:

  • (String) 


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# File 'lib/llm/agent.rb', line 379

def inspect
  "#<#{LLM::Utils.object_id(self)} " \
  "@llm=#{@llm.class}, @mode=#{mode.inspect}, @messages=#{messages.inspect}>"
end

#serialize(**kw) ⇒ void Also known as: save

This method returns an undefined value.



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# File 'lib/llm/agent.rb', line 387

def serialize(**kw)
  @ctx.serialize(**kw)
end

#deserialize(**kw) ⇒ Object Also known as: restore 



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# File 'lib/llm/agent.rb', line 395

def deserialize(**kw)
  @ctx.deserialize(**kw)
end