Encode a tool-parameter value for transmission in an Mcp-Param-* header.
Plain-ASCII values pass through; anything else (non-ASCII, control chars,
surrounding whitespace, or a value that looks like the sentinel) is wrapped
as =?base64?<base64-of-utf8>?=.
Encode a tool-parameter value for transmission in an Mcp-Param-* header. Plain-ASCII values pass through; anything else (non-ASCII, control chars, surrounding whitespace, or a value that looks like the sentinel) is wrapped as =?base64?<base64-of-utf8>?=.