Module: ClaudeAgentSDK

Defined in:
lib/claude_agent_sdk.rb,
lib/claude_agent_sdk/query.rb,
lib/claude_agent_sdk/types.rb,
lib/claude_agent_sdk/errors.rb,
lib/claude_agent_sdk/version.rb,
lib/claude_agent_sdk/streaming.rb,
lib/claude_agent_sdk/transport.rb,
lib/claude_agent_sdk/message_parser.rb,
lib/claude_agent_sdk/sdk_mcp_server.rb,
lib/claude_agent_sdk/subprocess_cli_transport.rb

Overview

Claude Agent SDK for Ruby

Defined Under Namespace

Modules: Streaming Classes: AgentDefinition, AssistantMessage, CLIConnectionError, CLIJSONDecodeError, CLINotFoundError, ClaudeAgentOptions, ClaudeSDKError, Client, HookMatcher, McpHttpServerConfig, McpSSEServerConfig, McpSdkServerConfig, McpStdioServerConfig, MessageParseError, MessageParser, PermissionResultAllow, PermissionResultDeny, PermissionRuleValue, PermissionUpdate, ProcessError, Query, ResultMessage, SdkMcpPrompt, SdkMcpResource, SdkMcpServer, SdkMcpTool, StreamEvent, SubprocessCLITransport, SystemMessage, TextBlock, ThinkingBlock, ToolPermissionContext, ToolResultBlock, ToolUseBlock, Transport, UserMessage

Constant Summary collapse

VERSION = 
'0.1.4'

Class Method Summary collapse

Class Method Details

.create_prompt(name:, description: nil, arguments: nil, &generator) ⇒ SdkMcpPrompt

Helper function to create a prompt definition

Examples:

Simple prompt

prompt = create_prompt(
  name: 'code_review',
  description: 'Review code for best practices'
) do |args|
  {
    messages: [
      {
        role: 'user',
        content: {
          type: 'text',
          text: 'Please review this code for best practices and suggest improvements.'
        }
      }
    ]
  }
end

Prompt with arguments

prompt = create_prompt(
  name: 'git_commit',
  description: 'Generate a git commit message',
  arguments: [
    { name: 'changes', description: 'Description of changes', required: true }
  ]
) do |args|
  {
    messages: [
      {
        role: 'user',
        content: {
          type: 'text',
          text: "Generate a concise git commit message for: #{args[:changes]}"
        }
      }
    ]
  }
end

Parameters:

  • name (String) —

    Unique identifier for the prompt

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

    Optional description

  • arguments (Array<Hash>, nil) (defaults to: nil) —

    Optional argument definitions

  • generator (Proc) —

    Block that generates prompt messages

Returns:

Raises:

  • (ArgumentError) 


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# File 'lib/claude_agent_sdk/sdk_mcp_server.rb', line 303

def self.create_prompt(name:, description: nil, arguments: nil, &generator)
  raise ArgumentError, 'Block required for prompt generator' unless generator

  SdkMcpPrompt.new(
    name: name,
    description: description,
    arguments: arguments,
    generator: generator
  )
end

.create_resource(uri:, name:, description: nil, mime_type: nil, &reader) ⇒ SdkMcpResource

Helper function to create a resource definition

Examples:

File resource

resource = create_resource(
  uri: 'file:///config/settings.json',
  name: 'Application Settings',
  description: 'Current application configuration',
  mime_type: 'application/json'
) do
  content = File.read('/path/to/settings.json')
  {
    contents: [{
      uri: 'file:///config/settings.json',
      mimeType: 'application/json',
      text: content
    }]
  }
end

Database resource

resource = create_resource(
  uri: 'db://users/count',
  name: 'User Count',
  description: 'Total number of registered users'
) do
  count = User.count
  {
    contents: [{
      uri: 'db://users/count',
      mimeType: 'text/plain',
      text: count.to_s
    }]
  }
end

Parameters:

  • uri (String) —

    Unique identifier for the resource (e.g., “file:///path/to/file”)

  • name (String) —

    Human-readable name

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

    Optional description

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

    Optional MIME type (e.g., “text/plain”, “application/json”)

  • reader (Proc) —

    Block that returns the resource content

Returns:

Raises:

  • (ArgumentError) 


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# File 'lib/claude_agent_sdk/sdk_mcp_server.rb', line 245

def self.create_resource(uri:, name:, description: nil, mime_type: nil, &reader)
  raise ArgumentError, 'Block required for resource reader' unless reader

  SdkMcpResource.new(
    uri: uri,
    name: name,
    description: description,
    mime_type: mime_type,
    reader: reader
  )
end

.create_sdk_mcp_server(name:, version: '1.0.0', tools: [], resources: [], prompts: []) ⇒ Hash

Create an SDK MCP server

Examples:

Simple calculator server

add_tool = ClaudeAgentSDK.create_tool('add', 'Add numbers', { a: :number, b: :number }) do |args|
  { content: [{ type: 'text', text: "Sum: #{args[:a] + args[:b]}" }] }
end

calculator = ClaudeAgentSDK.create_sdk_mcp_server(
  name: 'calculator',
  version: '2.0.0',
  tools: [add_tool]
)

options = ClaudeAgentOptions.new(
  mcp_servers: { calc: calculator },
  allowed_tools: ['mcp__calc__add']
)

Server with resources and prompts

config_resource = ClaudeAgentSDK.create_resource(
  uri: 'config://app',
  name: 'App Config'
) { { contents: [{ uri: 'config://app', text: 'config data' }] } }

review_prompt = ClaudeAgentSDK.create_prompt(
  name: 'review',
  description: 'Code review'
) { { messages: [{ role: 'user', content: { type: 'text', text: 'Review this' } }] } }

server = ClaudeAgentSDK.create_sdk_mcp_server(
  name: 'dev-tools',
  resources: [config_resource],
  prompts: [review_prompt]
)

Parameters:

  • name (String) —

    Unique identifier for the server

  • version (String) (defaults to: '1.0.0') —

    Server version (default: ‘1.0.0’)

  • tools (Array<SdkMcpTool>) (defaults to: []) —

    List of tool definitions

  • resources (Array<SdkMcpResource>) (defaults to: []) —

    List of resource definitions

  • prompts (Array<SdkMcpPrompt>) (defaults to: []) —

    List of prompt definitions

Returns:

  • (Hash) —

    MCP server configuration for ClaudeAgentOptions



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# File 'lib/claude_agent_sdk/sdk_mcp_server.rb', line 355

def self.create_sdk_mcp_server(name:, version: '1.0.0', tools: [], resources: [], prompts: [])
  server = SdkMcpServer.new(
    name: name,
    version: version,
    tools: tools,
    resources: resources,
    prompts: prompts
  )

  # Return configuration for ClaudeAgentOptions
  {
    type: 'sdk',
    name: name,
    instance: server
  }
end

.create_tool(name, description, input_schema, &handler) ⇒ SdkMcpTool

Helper function to create a tool definition

Examples:

Simple tool

tool = create_tool('greet', 'Greet a user', { name: :string }) do |args|
  { content: [{ type: 'text', text: "Hello, #{args[:name]}!" }] }
end

Tool with multiple parameters

tool = create_tool('add', 'Add two numbers', { a: :number, b: :number }) do |args|
  result = args[:a] + args[:b]
  { content: [{ type: 'text', text: "Result: #{result}" }] }
end

Tool with error handling

tool = create_tool('divide', 'Divide numbers', { a: :number, b: :number }) do |args|
  if args[:b] == 0
    { content: [{ type: 'text', text: 'Error: Division by zero' }], is_error: true }
  else
    result = args[:a] / args[:b]
    { content: [{ type: 'text', text: "Result: #{result}" }] }
  end
end

Parameters:

  • name (String) —

    Unique identifier for the tool

  • description (String) —

    Human-readable description

  • input_schema (Hash) —

    Schema defining input parameters

  • handler (Proc) —

    Block that implements the tool logic

Returns:

Raises:

  • (ArgumentError) 


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# File 'lib/claude_agent_sdk/sdk_mcp_server.rb', line 193

def self.create_tool(name, description, input_schema, &handler)
  raise ArgumentError, 'Block required for tool handler' unless handler

  SdkMcpTool.new(
    name: name,
    description: description,
    input_schema: input_schema,
    handler: handler
  )
end

.query(prompt:, options: nil) {|Message| ... } ⇒ Enumerator

Query Claude Code for one-shot or unidirectional streaming interactions

This function is ideal for simple, stateless queries where you don’t need bidirectional communication or conversation management.

Examples:

Simple query

ClaudeAgentSDK.query(prompt: "What is 2 + 2?") do |message|
  puts message
end

With options

options = ClaudeAgentSDK::ClaudeAgentOptions.new(
  allowed_tools: ['Read', 'Bash'],
  permission_mode: 'acceptEdits'
)
ClaudeAgentSDK.query(prompt: "Create a hello.rb file", options: options) do |msg|
  if msg.is_a?(ClaudeAgentSDK::AssistantMessage)
    msg.content.each do |block|
      puts block.text if block.is_a?(ClaudeAgentSDK::TextBlock)
    end
  end
end

Streaming input

messages = Streaming.from_array(['Hello', 'What is 2+2?', 'Thanks!'])
ClaudeAgentSDK.query(prompt: messages) do |message|
  puts message
end

Parameters:

  • prompt (String, Enumerator) —

    The prompt to send to Claude, or an Enumerator for streaming input

  • options (ClaudeAgentOptions) (defaults to: nil) —

    Optional configuration

Yields:

  • (Message) —

    Each message from the conversation

Returns:

  • (Enumerator) —

    if no block given



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# File 'lib/claude_agent_sdk.rb', line 50

def self.query(prompt:, options: nil, &block)
  return enum_for(:query, prompt: prompt, options: options) unless block

  options ||= ClaudeAgentOptions.new
  ENV['CLAUDE_CODE_ENTRYPOINT'] = 'sdk-rb'

  Async do
    transport = SubprocessCLITransport.new(prompt, options)
    begin
      transport.connect

      # If prompt is an Enumerator, write each message to stdin
      if prompt.is_a?(Enumerator) || prompt.respond_to?(:each)
        Async do
          begin
            prompt.each do |message_json|
              transport.write(message_json)
            end
          ensure
            transport.end_input
          end
        end
      end

      # Read and yield messages
      transport.read_messages do |data|
        message = MessageParser.parse(data)
        block.call(message)
      end
    ensure
      transport.close
    end
  end.wait
end