OpenAI models (e.g., GPT-5.2) fail to call MCP tools because they need
explicit system prompt context about available MCP servers and the
mcp--serverName--toolName naming convention. Claude and Gemini models
handle this from native tool definitions alone, but OpenAI models do not.
This commit adds a lightweight MCP SERVERS section to the system prompt
that includes:
- The mcp--serverName--toolName naming convention explanation
- A list of connected servers and their tool names
- Server-specific instructions (from the MCP protocol instructions field)
This does NOT duplicate tool schemas or descriptions (already provided
via native tool definitions), keeping the prompt compact.
Closes#11317