Anthropic

Advisor tool (secondary-model advisor) beta header.

Agent persistent memory beta header (Memory Stores API).

Beta header constants

1M context window beta header.

Extended / interleaved thinking betas.

Dreams (memory consolidation) beta header.

Research-preview API: request/response shapes may change without a deprecation period. Required by client.beta.dreams.* together with MANAGED_AGENTS_BETA (both auto-attached). Access is separately gated.

Primary fallback-credit beta. Tracks the latest official default (July 2026).

Fallback-credit beta header (June 2026). Kept for callers that pin the older bare-string credit-token behavior.

Fallback-credit beta header (July 2026) — required for object-form fallback_credit_token ({token, mode}) and used by default by BetaRefusalFallbackMiddleware.

Only valid string form of fallbacks (server-defined default chain).

Fast mode beta header.

MCP Tunnels beta header (research preview).

Required by client.beta.tunnels.* and client.beta.tunnels.certificates.*. Supersedes Admin API /v1/organizations/tunnels during a migration window. Management calls need WIF with workspace:manage_tunnels — not API keys.

Surfaces model_context_window_exceeded as a recoverable stop_reason.

Shorthand helper for accessing model IDs via symbols

Anthropic::Model::CLAUDE_SONNET # => "claude-sonnet-5"
Anthropic::Model::CLAUDE_FABLE  # => "claude-fable-5"
Anthropic::Model::CLAUDE_OPUS   # => "claude-opus-5"
Anthropic::Model::CLAUDE_HAIKU  # => "claude-haiku-4-5"

Anthropic.model_name(:sonnet) # => "claude-sonnet-5"
Anthropic.model_name(:fable)  # => "claude-fable-5"
Anthropic.model_name(:mythos) # => "claude-mythos-5"
Anthropic.model_name(:opus)   # => "claude-opus-5"
Anthropic.model_name(:opus_5) # => "claude-opus-5"
Anthropic.model_name(:haiku)  # => "claude-haiku-4-5-20251001"

Output token cap betas.

PDF document support beta header.

Primary server-side fallbacks beta. Tracks the latest official default (July 2026). Auto-attached when fallbacks: is set.

Server-side fallbacks beta header (June 2026).

Prefer SERVER_SIDE_FALLBACK_BETA / SERVER_SIDE_FALLBACK_BETA_2026_07_01 for new code; this constant is kept for callers that pin the older header.

Server-side fallbacks beta header (July 2026) — supports fallbacks: "default" and aligns with the official Python/Ruby/TS SDKs.

Thinking token count in streaming deltas (optional display).

User profiles beta header.

Collect the beta header strings required by a set of server tools.

This is the single source of truth for server-tool-to-beta mappings so that resource classes don't have to duplicate the case logic.

Returns true when fallbacks is a non-empty chain or the string "default".

Any other string (including empty) is treated as absent so we do not auto-attach the server-side fallback beta for typos like "defaults". Serialization via FallbacksParamConverter also rejects non-"default" strings with ArgumentError.

Convenience method to create an output schema

output = Anthropic.output_schema(
  name: "weather_report",
  schema: {
    "temperature" => Schema.number("Current temperature"),
    "conditions"  => Schema.string("Weather conditions"),
  },
  required: ["temperature", "conditions"]
)

Resolve and compile the complete "anthropic-beta" headers mapping

Helper method for creating inline tools with Schema DSL

weather_tool = Anthropic.tool(
  name: "get_weather",
  description: "Get current weather for a location",
  schema: {
    "location" => Schema.string("City name, e.g. San Francisco, CA"),
    "unit"     => Schema.enum("celsius", "fahrenheit", description: "Temperature unit"),
  },
  required: ["location"]
) do |input|
  location = input["location"].as_s
  unit = input["unit"]?.try(&.as_s) || "fahrenheit"
  "The weather in #{location} is sunny and 72°#{unit == "celsius" ? "C" : "F"}."
end

Macro to create a typed output schema from a struct

struct MyOutput
  include JSON::Serializable
  getter result : String
  getter confidence : Float64
end

schema = Anthropic.output_schema(type: MyOutput, name: "my_output")

Macro to create typed tools with struct input

This provides Ruby BaseTool-like functionality where:

• Input schema is derived from a Crystal struct
• Handler receives typed struct instead of JSON::Any
• Field descriptions come from @[JSON::Field(description: "...")]

struct SearchInput
  include JSON::Serializable
  getter query : String
  getter category : Category?
end

tool = Anthropic.tool(
  name: "search",
  description: "Search products",
  input: SearchInput
) do |input|
  "Found results for #{input.query}"
end