Update mcp_agent.secrets.yaml.example for clarity

Uncomment sections for API keys and provide guidance on environment variable usage.

Author: saqadri

src/mcp_agent/data/examples/basic/mcp_basic_agent/mcp_agent.secrets.yaml.example

@@ -3,30 +3,32 @@ $schema: https://raw.githubusercontent.com/lastmile-ai/mcp-agent/refs/heads/main
 # Copy this file to mcp_agent.secrets.yaml and fill in your API keys.
 # This file should be gitignored.
 
-openai:
-  api_key: "sk-your-openai-key"
+# UNCOMMENT the sections to specify secrets that you need.
+# Alternatively, if you have env set (e.g. ANTHROPIC_API_KEY or OPENAI_API_KEY), that will be picked up as well.
+# OpenAI API
+# openai:
+#  api_key: "sk-your-openai-key"
 
-anthropic:
-  api_key: "sk-your-anthropic-key"
+# Anthropic API
+# anthropic:
+#  api_key: "sk-your-anthropic-key"
 
-# Optional: Azure OpenAI
+# Azure LLM inference
 # azure:
 #   api_key: "..."
 #   endpoint: "https://<your-endpoint>.openai.azure.com"
 
-# Optional: Google
+# Google LLM inference (Vertex AI, Gemini, etc.)
 # google:
 #   api_key: "..."
 #   # vertexai: true
 #   # project: your-gcp-project-id
 #   # location: us-central1
 
-# Optional: AWS / Bedrock
+# AWS / Bedrock inference
 # bedrock:
 #   aws_access_key_id: "..."
 #   aws_secret_access_key: "..."
 #   aws_region: "us-east-1"
 #   # aws_session_token: "..."
 #   # profile: "default"
-
-