feat(models): add Anthropic provider support

README.md

@@ -114,7 +114,7 @@ A bug report comes in. You have the exact YAML config. Load it, replay it, debug
 |---------|-------------|
 | **YAML-first config** | Models, agents, tools, hooks, MCP, orchestrations — all in one file |
 | **Full YAML power** | Variables (`${VAR:-default}`), anchors (`&ref` / `*ref`), `x-` scratch pads, multi-file merge |
-| **Multi-model support** | Bedrock, OpenAI, Ollama, Gemini — swap with one line |
+| **Multi-model support** | Bedrock, Anthropic, OpenAI, Ollama, Gemini — swap with one line |
 | **MCP servers & clients** | Launch local servers from Python files, connect to remote HTTP endpoints, or spawn stdio subprocesses |
 | **MCP lifecycle management** | Startup ordering, readiness polling, graceful shutdown — servers before clients, always |
 | **Orchestration modes** | Delegate (agent-as-tool), Swarm (peer handoffs), Graph (DAG pipelines) — arbitrarily nestable |

docs/configuration/Chapter_02.md

@@ -14,7 +14,7 @@ models:
 
   creative:
     provider: openai
-    model_id: gpt-4o
+    model_id: gpt-5.5
     params:
       temperature: 0.9
 
@@ -30,9 +30,26 @@ models:
 | Provider | Package Required | Example `model_id` |
 |----------|-----------------|---------------------|
 | `bedrock` | *(included)* | `us.anthropic.claude-sonnet-4-6-v1:0` |
-| `openai` | `pip install strands-compose[openai]` | `gpt-4o` |
+| `openai` | `pip install strands-compose[openai]` | `gpt-5.5` |
 | `ollama` | `pip install strands-compose[ollama]` | `llama3.2` |
-| `gemini` | `pip install strands-compose[gemini]` | `gemini-2.0-flash` |
+| `gemini` | `pip install strands-compose[gemini]` | `gemini-3.6-flash` |
+| `anthropic` | `pip install strands-compose[anthropic]` | `claude-sonnet-4-6` |
+
+> **Anthropic note:** the `anthropic` provider talks to the Anthropic API directly
+> (not through Bedrock) and **requires `max_tokens` in `params`** — the API mandates
+> it, unlike the other providers:
+>
+> ```yaml
+> models:
+>   claude:
+>     provider: anthropic
+>     model_id: claude-sonnet-4-6
+>     params:
+>       max_tokens: 4096          # required by the Anthropic API
+> ```
+>
+> Set the API key via the `ANTHROPIC_API_KEY` environment variable, or pass
+> `params.client_args.api_key`.
 
 ## How Agents Reference Models
 
@@ -97,7 +114,7 @@ models:
 
 > **Tips & Tricks**
 >
-> - When combined with `vars`, you can swap models at runtime: `MODEL=gpt-4o python main.py`. See [Chapter 3](Chapter_03.md).
+> - When combined with `vars`, you can swap models at runtime: `MODEL=gpt-5.5 python main.py`. See [Chapter 3](Chapter_03.md).
 > - If you omit `model` on an agent entirely, strands picks its built-in default (Bedrock). This is fine for quick tests but explicit is better for production.
 > - The `params` dict preserves types from YAML — integers stay integers, floats stay floats. This matters for parameters like `max_tokens` that must be an int.
 

docs/configuration/Chapter_18.md

@@ -24,7 +24,7 @@ log_level: "WARNING"  # Optional: DEBUG, INFO, WARNING, ERROR
 ```yaml
 models:
   name:
-    provider: bedrock | openai | ollama | gemini | module.path:CustomModel
+    provider: bedrock | anthropic | openai | ollama | gemini | module.path:CustomModel
     model_id: "model-identifier"
     params: {}        # Provider-specific kwargs
 ```

pyproject.toml

@@ -44,6 +44,9 @@ openai = [
 gemini = [
     "strands-agents[gemini]>=1.35.0,<2.0.0",
 ]
+anthropic = [
+    "strands-agents[anthropic]>=1.35.0,<2.0.0",
+]
 
 [project.urls]
 Homepage = "https://github.com/strands-compose/sdk-python"

src/strands_compose/config/loaders/loaders.py

@@ -66,15 +66,12 @@ def normalize(raw: dict) -> dict:
     """
     raw = dict(raw)  # do not mutate the input
     version = str(raw.get("version", "1"))
-    match version:
-        case "1":
-            pass  # current canonical schema
-        case _:
-            raise ValueError(
-                f"This config declares schema version '{version}', but this "
-                f"strands-compose version only supports version '1'.\n"
-                f"Upgrade: pip install --upgrade strands-compose"
-            )
+    if version != "1":
+        raise ValueError(
+            f"This config declares schema version '{version}', but this "
+            f"strands-compose version only supports version '1'.\n"
+            f"Upgrade: pip install --upgrade strands-compose"
+        )
     raw["version"] = "1"
     return raw
 

src/strands_compose/config/resolvers/models.py

@@ -19,8 +19,9 @@
 def resolve_model(model_def: ModelDef) -> Model:
     """Resolve a ModelDef to a strands model instance.
 
-    Built-in providers (``"ollama"``, ``"bedrock"``, ``"openai"``,
-    ``"gemini"``) are dispatched via :func:`~strands_compose.models.create_model`.
+    Built-in providers (``"bedrock"``, ``"anthropic"``, ``"ollama"``,
+    ``"openai"``, ``"gemini"``) are dispatched via
+    :func:`~strands_compose.models.create_model`.
     Any other ``provider`` value is treated as an import spec
     (``module.path:ClassName``) for a custom :class:`~strands.models.Model`
     subclass.

src/strands_compose/models.py

@@ -6,14 +6,14 @@
 
 from strands.models import Model
 
-PROVIDERS = ("bedrock", "ollama", "openai", "gemini")
+PROVIDERS = ("bedrock", "ollama", "openai", "gemini", "anthropic")
 
 
 def create_model(provider: str, model_id: str, **params: Any) -> Model:
     """Dispatch to the appropriate model factory by provider name.
 
     Args:
-        provider: ``"ollama"`` or ``"bedrock"`` or ``"openai"`` or ``"gemini"``.
+        provider: ``"bedrock"``, ``"anthropic"``, ``"ollama"``, ``"openai"``, ``"gemini"``.
         model_id: Model identifier.
         **params: Provider-specific keyword arguments.
 
@@ -24,46 +24,54 @@ def create_model(provider: str, model_id: str, **params: Any) -> Model:
         ValueError: If the provider is unknown.
         ImportError: If a required optional provider package is not installed.
     """
-    match provider.lower():
-        case "bedrock":
-            from strands.models.bedrock import BedrockModel
+    provider_name = provider.lower()
+    if provider_name == "bedrock":
+        from strands.models.bedrock import BedrockModel
 
-            return BedrockModel(model_id=model_id, **params)
+        return BedrockModel(model_id=model_id, **params)
 
-        case "ollama":
-            try:
-                from strands.models.ollama import OllamaModel
-            except ImportError:
-                raise ImportError(
-                    "The 'ollama' provider requires the ollama extra:\n"
-                    "  pip install strands-compose[ollama]\n"
-                    "Or install directly: pip install strands-agents[ollama]"
-                ) from None
-            return OllamaModel(model_id=model_id, **params)
+    if provider_name == "ollama":
+        try:
+            from strands.models.ollama import OllamaModel
+        except ImportError:
+            raise ImportError(
+                "The 'ollama' provider requires the ollama extra:\n"
+                "  pip install strands-compose[ollama]\n"
+                "Or install directly: pip install strands-agents[ollama]"
+            ) from None
+        return OllamaModel(model_id=model_id, **params)
 
-        case "openai":
-            try:
-                from strands.models.openai import OpenAIModel
-            except ImportError:
-                raise ImportError(
-                    "The 'openai' provider requires the openai extra:\n"
-                    "  pip install strands-compose[openai]\n"
-                    "Or install directly: pip install strands-agents[openai]"
-                ) from None
-            return OpenAIModel(model_id=model_id, **params)
+    if provider_name == "openai":
+        try:
+            from strands.models.openai import OpenAIModel
+        except ImportError:
+            raise ImportError(
+                "The 'openai' provider requires the openai extra:\n"
+                "  pip install strands-compose[openai]\n"
+                "Or install directly: pip install strands-agents[openai]"
+            ) from None
+        return OpenAIModel(model_id=model_id, **params)
 
-        case "gemini":
-            try:
-                from strands.models.gemini import GeminiModel
-            except ImportError:
-                raise ImportError(
-                    "The 'gemini' provider requires the gemini extra:\n"
-                    "  pip install strands-compose[gemini]\n"
-                    "Or install directly: pip install strands-agents[gemini]"
-                ) from None
-            return GeminiModel(model_id=model_id, **params)
+    if provider_name == "gemini":
+        try:
+            from strands.models.gemini import GeminiModel
+        except ImportError:
+            raise ImportError(
+                "The 'gemini' provider requires the gemini extra:\n"
+                "  pip install strands-compose[gemini]\n"
+                "Or install directly: pip install strands-agents[gemini]"
+            ) from None
+        return GeminiModel(model_id=model_id, **params)
 
-        case _:
-            raise ValueError(
-                f"Unknown model provider '{provider}'.\nAvailable: {', '.join(PROVIDERS)}."
-            )
+    if provider_name == "anthropic":
+        try:
+            from strands.models.anthropic import AnthropicModel
+        except ImportError:
+            raise ImportError(
+                "The 'anthropic' provider requires the anthropic extra:\n"
+                "  pip install strands-compose[anthropic]\n"
+                "Or install directly: pip install strands-agents[anthropic]"
+            ) from None
+        return AnthropicModel(model_id=model_id, **params)
+
+    raise ValueError(f"Unknown model provider '{provider}'.\nAvailable: {', '.join(PROVIDERS)}.")

tests/factories.py

@@ -65,7 +65,7 @@ def graph_orchestration(
     entry_name: str, edges: list[tuple[str, str]], **overrides: Any
 ) -> GraphOrchestrationDef:
     """Build a graph orchestration from ``(from, to)`` edge tuples."""
-    edge_defs = [GraphEdgeDef(from_agent=a, to_agent=b) for a, b in edges]  # ty: ignore[unknown-argument, missing-argument]
+    edge_defs = [GraphEdgeDef(from_agent=a, to_agent=b) for a, b in edges]
     return GraphOrchestrationDef(entry_name=entry_name, edges=edge_defs, **overrides)