[tiny-agents] Configure inference API key from inputs + keep empty dicts in chat completion payload (#3226)

* allow passing api key for inference in tiny-agents

* keep empty dicts in chat completion payload

* fix test

* re-add check

* Apply suggestions from code review

Co-authored-by: Lucain <lucain@huggingface.co>

---------

Co-authored-by: Lucain <lucain@huggingface.co>

Author: hanouticelina

src/huggingface_hub/inference/_mcp/cli.py

@@ -71,6 +71,8 @@ def _sigint_handler() -> None:
             signal.signal(signal.SIGINT, lambda *_: _sigint_handler())
 
         # Handle inputs (i.e. env variables injection)
+        resolved_inputs: dict[str, str] = {}
+
         if len(inputs) > 0:
             print(
                 "[bold blue]Some initial inputs are required by the agent. "
@@ -79,19 +81,26 @@ def _sigint_handler() -> None:
             for input_item in inputs:
                 input_id = input_item["id"]
                 description = input_item["description"]
-                env_special_value = "${input:" + input_id + "}"  # Special value to indicate env variable injection
+                env_special_value = f"${{input:{input_id}}}"
 
-                # Check env variables that will use this input
-                input_vars = set()
+                # Check if the input is used by any server or as an apiKey
+                input_usages = set()
                 for server in servers:
                     # Check stdio's "env" and http/sse's "headers" mappings
                     env_or_headers = server.get("env", {}) if server["type"] == "stdio" else server.get("headers", {})
                     for key, value in env_or_headers.items():
                         if env_special_value in value:
-                            input_vars.add(key)
+                            input_usages.add(key)
+
+                raw_api_key = config.get("apiKey")
+                if isinstance(raw_api_key, str) and env_special_value in raw_api_key:
+                    input_usages.add("apiKey")
 
-                if not input_vars:
-                    print(f"[yellow]Input {input_id} defined in config but not used by any server.[/yellow]")
+                if not input_usages:
+                    print(
+                        f"[yellow]Input '{input_id}' defined in config but not used by any server or as an API key."
+                        " Skipping.[/yellow]"
+                    )
                     continue
 
                 # Prompt user for input
@@ -104,30 +113,39 @@ def _sigint_handler() -> None:
                 if exit_event.is_set():
                     return
 
-                # Inject user input (or env variable) into stdio's env or http/sse's headers
+                # Fallback to environment variable when user left blank
+                final_value = user_input
+                if not final_value:
+                    final_value = os.getenv(env_variable_key, "")
+                    if final_value:
+                        print(f"[green]Value successfully loaded from '{env_variable_key}'[/green]")
+                    else:
+                        print(
+                            f"[yellow]No value found for '{env_variable_key}' in environment variables. Continuing.[/yellow]"
+                        )
+                resolved_inputs[input_id] = final_value
+
+                # Inject resolved value (can be empty) into stdio's env or http/sse's headers
                 for server in servers:
                     env_or_headers = server.get("env", {}) if server["type"] == "stdio" else server.get("headers", {})
                     for key, value in env_or_headers.items():
                         if env_special_value in value:
-                            if user_input:
-                                env_or_headers[key] = env_or_headers[key].replace(env_special_value, user_input)
-                            else:
-                                value_from_env = os.getenv(env_variable_key, "")
-                                env_or_headers[key] = env_or_headers[key].replace(env_special_value, value_from_env)
-                                if value_from_env:
-                                    print(f"[green]Value successfully loaded from '{env_variable_key}'[/green]")
-                                else:
-                                    print(
-                                        f"[yellow]No value found for '{env_variable_key}' in environment variables. Continuing.[/yellow]"
-                                    )
+                            env_or_headers[key] = env_or_headers[key].replace(env_special_value, final_value)
 
             print()
 
+        raw_api_key = config.get("apiKey")
+        if isinstance(raw_api_key, str):
+            substituted_api_key = raw_api_key
+            for input_id, val in resolved_inputs.items():
+                substituted_api_key = substituted_api_key.replace(f"${{input:{input_id}}}", val)
+            config["apiKey"] = substituted_api_key
         # Main agent loop
         async with Agent(
             provider=config.get("provider"),  # type: ignore[arg-type]
             model=config.get("model"),
             base_url=config.get("endpointUrl"),  # type: ignore[arg-type]
+            api_key=config.get("apiKey"),
             servers=servers,  # type: ignore[arg-type]
             prompt=prompt,
         ) as agent:

src/huggingface_hub/inference/_mcp/constants.py

@@ -56,12 +56,7 @@
             "description": "Call this tool when the task given by the user is complete",
             "parameters": {
                 "type": "object",
-                "properties": {
-                    "trigger": {
-                        "type": "boolean",
-                        "description": "Set to true to trigger this function",
-                    }
-                },
+                "properties": {},
             },
         },
     }
@@ -75,12 +70,7 @@
             "description": "Ask the user for more info required to solve or clarify their problem.",
             "parameters": {
                 "type": "object",
-                "properties": {
-                    "trigger": {
-                        "type": "boolean",
-                        "description": "Set to true to trigger this function",
-                    }
-                },
+                "properties": {},
             },
         },
     }

src/huggingface_hub/inference/_mcp/types.py

@@ -1,5 +1,7 @@
 from typing import Dict, List, Literal, TypedDict, Union
 
+from typing_extensions import NotRequired
+
 
 class InputConfig(TypedDict, total=False):
     id: str
@@ -35,5 +37,6 @@ class SSEServerConfig(TypedDict):
 class AgentConfig(TypedDict):
     model: str
     provider: str
+    apiKey: NotRequired[str]
     inputs: List[InputConfig]
     servers: List[ServerConfig]

src/huggingface_hub/inference/_providers/_common.py

@@ -51,9 +51,6 @@ def filter_none(obj: Union[Dict[str, Any], List[Any]]) -> Union[Dict[str, Any],
                 continue
             if isinstance(v, (dict, list)):
                 v = filter_none(v)
-                # remove empty nested dicts
-                if isinstance(v, dict) and not v:
-                    continue
             cleaned[k] = v
         return cleaned
 

tests/test_inference_providers.py

@@ -645,7 +645,7 @@ def test_prepare_request(self, mocker):
         assert request.task == "text-classification"
         assert request.model == "username/repo_name"
         assert request.headers["authorization"] == "Bearer hf_test_token"
-        assert request.json == {"inputs": "this is a dummy input"}
+        assert request.json == {"inputs": "this is a dummy input", "parameters": {}}
 
     def test_prepare_request_conversational(self, mocker):
         mocker.patch(
@@ -1445,10 +1445,10 @@ def test_recursive_merge(dict1: Dict, dict2: Dict, expected: Dict):
         ({}, {}),  # empty dictionary remains empty
         ({"a": 1, "b": None, "c": 3}, {"a": 1, "c": 3}),  # remove None at root level
         ({"a": None, "b": {"x": None, "y": 2}}, {"b": {"y": 2}}),  # remove nested None
-        ({"a": {"b": {"c": None}}}, {}),  # remove empty nested dict
+        ({"a": {"b": {"c": None}}}, {"a": {"b": {}}}),  # keep empty nested dict
         (
             {"a": "", "b": {"x": {"y": None}, "z": 0}, "c": []},  # do not remove 0, [] and "" values
-            {"a": "", "b": {"z": 0}, "c": []},
+            {"a": "", "b": {"x": {}, "z": 0}, "c": []},
         ),
         (
             {"a": [0, 1, None]},  # do not remove None in lists