113 lines
2.9 KiB
Markdown
113 lines
2.9 KiB
Markdown
# Claude API — Ruby
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> **Note:** The Ruby SDK supports the Claude API. A tool runner is available in beta via `client.beta.messages.tool_runner()`. Agent SDK is not yet available for Ruby.
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## Installation
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```bash
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gem install anthropic
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```
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## Client Initialization
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```ruby
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require "anthropic"
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# Default (uses ANTHROPIC_API_KEY env var)
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client = Anthropic::Client.new
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# Explicit API key
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client = Anthropic::Client.new(api_key: "your-api-key")
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```
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---
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## Basic Message Request
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```ruby
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message = client.messages.create(
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model: :"claude-opus-4-7",
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max_tokens: 16000,
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messages: [
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{ role: "user", content: "What is the capital of France?" }
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]
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)
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# content is an array of polymorphic block objects (TextBlock, ThinkingBlock,
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# ToolUseBlock, ...). .type is a Symbol — compare with :text, not "text".
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# .text raises NoMethodError on non-TextBlock entries.
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message.content.each do |block|
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puts block.text if block.type == :text
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end
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```
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---
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## Streaming
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```ruby
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stream = client.messages.stream(
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model: :"claude-opus-4-7",
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max_tokens: 64000,
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messages: [{ role: "user", content: "Write a haiku" }]
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)
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stream.text.each { |text| print(text) }
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```
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---
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## Tool Use
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The Ruby SDK supports tool use via raw JSON schema definitions and also provides a beta tool runner for automatic tool execution.
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### Tool Runner (Beta)
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```ruby
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class GetWeatherInput < Anthropic::BaseModel
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required :location, String, doc: "City and state, e.g. San Francisco, CA"
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end
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class GetWeather < Anthropic::BaseTool
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doc "Get the current weather for a location"
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input_schema GetWeatherInput
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def call(input)
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"The weather in #{input.location} is sunny and 72°F."
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end
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end
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client.beta.messages.tool_runner(
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model: :"claude-opus-4-7",
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max_tokens: 16000,
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tools: [GetWeather.new],
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messages: [{ role: "user", content: "What's the weather in San Francisco?" }]
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).each_message do |message|
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puts message.content
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end
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```
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### Manual Loop
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See the [shared tool use concepts](../shared/tool-use-concepts.md) for the tool definition format and agentic loop pattern.
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---
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## Prompt Caching
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`system_:` (trailing underscore — avoids shadowing `Kernel#system`) takes an array of text blocks; set `cache_control` on the last block. Plain hashes work via the `OrHash` type alias. For placement patterns and the silent-invalidator audit checklist, see `shared/prompt-caching.md`.
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```ruby
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message = client.messages.create(
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model: :"claude-opus-4-7",
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max_tokens: 16000,
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system_: [
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{ type: "text", text: long_system_prompt, cache_control: { type: "ephemeral" } }
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],
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messages: [{ role: "user", content: "Summarize the key points" }]
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)
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```
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For 1-hour TTL: `cache_control: { type: "ephemeral", ttl: "1h" }`. There's also a top-level `cache_control:` on `messages.create` that auto-places on the last cacheable block.
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Verify hits via `message.usage.cache_creation_input_tokens` / `message.usage.cache_read_input_tokens`.
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