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 ChatClientConfig when you need a custom Anthropic base URL; ANTHROPIC_ENDPOINT is not a source-registered alias.

Runtime Chat Options

Use HPD ChatClientConfig for normal model-call behavior. Agent-level defaults belong in AgentConfig.Clients.Chat; complete per-run replacements belong in AgentRunConfig.Clients.Chat.

using HPD.Agent;
using HPD.Agent.Providers.Anthropic;
var agent = await new AgentBuilder()
    .WithAnthropic(model: "claude-3-5-sonnet-latest")

    .BuildAsync();

Use AgentRunConfig.Clients.Chat.ProviderKey and ModelName for selection. Use runtime chat options for 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 ChatClientConfig.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
{
    Clients = new AgentClientsConfig
    {
        Chat = new ChatClientConfig
        {
            ProviderKey = "anthropic",
            ModelName = "claude-3-5-sonnet-latest",
            Reasoning = new ReasoningOptions
            {
                Effort = ReasoningEffort.High
            }
        }
    }
};

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

In stored config, put Anthropic request options in the typed providerOptions payload, not in ProviderConfig:

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

Caveats

Runtime validation checks model and endpoint. Credentials are resolved lazily when a run first acquires this provider client; a missing credential fails that run, not BuildAsync(). Anthropic chat uses the Anthropic SDK's MEAI chat client.