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Enabled when ANTHROPIC_API_KEY is set in your environment.

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Overview

The @standardagents/anthropic package provides the Anthropic provider factory for Standard Agents. It wraps the official @anthropic-ai/sdk and enables direct access to Claude models with typed providerOptions, extended thinking support, prompt caching, and Anthropic’s server-side web search tool.

Key Features

  • Direct Anthropic Messages API access with automatic client management
  • Typed providerOptions with TypeScript autocompletion
  • Extended thinking support across model generations (adaptive on Claude 4.6+, token budgets on Claude 4.0-4.5)
  • Thinking blocks round-trip correctly in multi-turn tool conversations
  • Built-in web_search provider tool (executed on Anthropic’s servers)
  • Live model listing and capability detection via the Anthropic Models API
  • Prompt caching opt-in for the system prompt

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Installation

npm
npm install @standardagents/anthropic
pnpm
pnpm add @standardagents/anthropic
yarn
yarn add @standardagents/anthropic

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Quick Start

agents/models/claude_opus.ts
import { defineModel } from '@standardagents/spec';
import { anthropic } from '@standardagents/anthropic';

export default defineModel({
  name: 'claude-opus',
  provider: anthropic,
  model: 'claude-opus-4-8',
  inputPrice: 5.00,
  outputPrice: 25.00,
});

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Provider Factory

The anthropic export is a provider factory function that creates Anthropic provider instances: 
import { anthropic } from '@standardagents/anthropic';

// The factory is used by defineModel internally
defineModel({
  name: 'my-model',
  provider: anthropic,  // Pass the factory, not a string
  model: 'claude-sonnet-4-6',
});

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Provider Options

The anthropic factory includes a typed schema for provider-specific options: 
import { defineModel } from '@standardagents/spec';
import { anthropic } from '@standardagents/anthropic';

export default defineModel({
  name: 'claude-opus',
  provider: anthropic,
  model: 'claude-opus-4-8',
  inputPrice: 5.00,
  outputPrice: 25.00,
  providerOptions: {
    service_tier: 'auto',
    metadata: { user_id: 'user-123' },
    cacheSystemPrompt: true,
  },
});

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Available Options

OptionTypeDescription
service_tier'auto' | 'standard_only'Request priority tier
metadata{ user_id?: string }Opaque user identifier for abuse monitoring
cacheSystemPromptbooleanAdd a prompt-caching breakpoint to the system prompt so repeated requests bill cached-input rates
thinkingobjectExplicit thinking configuration override (Anthropic API shape, e.g. { type: 'adaptive' } or { type: 'enabled', budget_tokens: 8192 })
Unknown keys are passed through to the Messages API for forward compatibility.

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Extended Thinking

The provider maps the Standard Agents 0-100 reasoning level to the right thinking configuration per model generation:
Model familyThinking modeMapping
Claude Fable 5, Opus 4.6-4.8, Sonnet 4.6Adaptivethinking: { type: 'adaptive' } + output_config.effort (low / medium / high)
Opus 4.0-4.5, Sonnet 4.0-4.5, Haiku 4.5, Sonnet 3.7Token budgetthinking: { type: 'enabled', budget_tokens } scaled to the output limit
Claude 3.xNoneThinking is not requested
Thinking text, signatures, and redacted thinking blocks are preserved on responses and replayed exactly on subsequent turns, which Anthropic requires for multi-turn tool use with thinking enabled. When thinking is active, sampling parameters (temperature, top_p, top_k) are automatically omitted since the API rejects them alongside thinking.

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Provider Tools

Anthropic’s server-side web_search tool is exposed as a provider-embedded tool. Add it to a prompt or model’s tool list and Claude will search the web on Anthropic’s servers; results are recorded in execution logs as provider tool calls with their queries and sources.

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Usage & Cost Tracking

Token usage is normalized to the Standard Agents convention: promptTokens covers the full prompt (including cache reads and cache writes), cachedTokens reports tokens served from the prompt cache, and reasoningTokens reports thinking tokens. Raw Anthropic usage buckets (cacheCreationInputTokens, cacheReadInputTokens, serviceTier, server tool usage) are preserved in response metadata for inspection. The Anthropic API reports token counts but no dollar cost, so the provider derives the exact request cost for documented Claude models from the raw billing buckets — uncached input at the base rate, cache writes at 1.25x (5-minute TTL) or 2x (1-hour TTL), cache reads at 0.1x, and output (including thinking tokens) at the output rate. This provider-reported cost takes precedence over a flat inputPrice/outputPrice calculation, so you do not need to set prices on models in the known-pricing table. For custom or future model IDs without table entries, set inputPrice and outputPrice on the model definition.

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Supported Models

All Claude models are supported (model IDs starting with claude-). The model picker lists live data from the Anthropic Models API, including context window, output limits, and per-model capabilities. API Key: Set ANTHROPIC_API_KEY environment variable Package: @standardagents/anthropic