Anthropic

The Anthropic provider uses provider key anthropic and the HPD-Agent.Providers.Anthropic package. ModelName is a Claude model id.

Set an API key:

export ANTHROPIC_API_KEY="..."

Use fluent setup first:

using HPD.Agent;
using HPD.Agent.Providers.Anthropic;

var agent = await new AgentBuilder()
    .WithAnthropic(model: "claude-3-5-sonnet-latest")
    .BuildAsync();

var result = await agent.RunAsync("Write one sentence about Anthropic setup.");
Console.WriteLine(result.Text);

The equivalent Clients.Chat shape is:

{
  "Clients": {
    "Chat": {
      "ProviderKey": "anthropic",
      "ModelName": "claude-3-5-sonnet-latest"
    }
  }
}

The default endpoint is Anthropic's API. Set Endpoint explicitly in ClientProviderConfig when you need a custom Anthropic base URL; ANTHROPIC_ENDPOINT is not a source-registered alias.

Runtime Chat Options

Use HPD ChatRunConfig for normal model-call behavior. Agent-level defaults belong in ClientProviderConfig.ChatDefaults; per-run or per-session overrides belong in AgentRunConfig.Chat.

using HPD.Agent;
using HPD.Agent.Providers.Anthropic;
var agent = await new AgentBuilder()
    .WithAnthropic(model: "claude-3-5-sonnet-latest")
    .WithChatDefaults(new ChatRunConfig
    {
        Temperature = 0.2,
        MaxOutputTokens = 4096,
        Reasoning = new ReasoningOptions
        {
            Effort = ReasoningEffort.High
        }
    })
    .BuildAsync();

Use runtime chat options for model selection, temperature, top-p, max output tokens, stop sequences, response format, tools, tool mode, seed, and generic reasoning options.

Anthropic Chat Request Options

Use AnthropicChatRequestOptions for Anthropic-only request properties:

Option	Purpose
ServiceTier	Sets Anthropic request service tier, such as auto or standard_only.
ThinkingBudgetTokens	Sets an exact Anthropic extended-thinking token budget. Use generic ChatRunConfig.Reasoning for normal reasoning control.
ThinkingDisplay	Controls Anthropic thinking display, such as summarized or omitted, when using ThinkingBudgetTokens.
CacheControl	Adds Anthropic prompt-cache markers to supported text content blocks.

CacheControl has its own options:

Option	Purpose
SystemMessages	Applies Anthropic prompt-cache control to system-message text blocks.
LastUserMessage	Applies Anthropic prompt-cache control to text blocks on the final user message in the request.

Cache TTL values are FiveMinutes (5m in JSON) and OneHour (1h in JSON).

In C#:

using HPD.Agent;
using HPD.Agent.Providers.Anthropic;

var agent = await new AgentBuilder()
    .WithAnthropic(model: "claude-3-5-sonnet-latest")
    .WithAnthropicChatRequestOptions(anthropic =>
    {
        anthropic.ServiceTier = AnthropicServiceTier.Auto;
        anthropic.CacheControl = new AnthropicCacheControlConfig
        {
            SystemMessages = AnthropicCacheTtl.OneHour,
            LastUserMessage = AnthropicCacheTtl.FiveMinutes
        };
    })
    .BuildAsync();

Per run:

var runConfig = new AgentRunConfig
{
    Chat = new ChatRunConfig
    {
        Reasoning = new ReasoningOptions
        {
            Effort = ReasoningEffort.High
        }
    }
};

runConfig.Chat.UseAnthropicChatRequestOptions(new AnthropicChatRequestOptions
{
    ServiceTier = AnthropicServiceTier.Auto,
    ThinkingBudgetTokens = 4096,
    ThinkingDisplay = AnthropicThinkingDisplay.Summarized
});

In stored config, put Anthropic request options in chat defaults or per-run chat additional properties, not in ProviderOptions:

{
  "Clients": {
    "Chat": {
      "ProviderKey": "anthropic",
      "ModelName": "claude-3-5-sonnet-latest",
      "ChatDefaults": {
        "AdditionalProperties": {
          "serviceTier": "auto",
          "thinkingBudgetTokens": 4096,
          "thinkingDisplay": "summarized",
          "cacheControl": {
            "systemMessages": "1h",
            "lastUserMessage": "5m"
          }
        }
      }
    }
  }
}

Caveats

Validation checks API key, model, and endpoint. Missing credentials fail at BuildAsync() before a live model call. Anthropic chat uses the Anthropic SDK's MEAI chat client.