[BUG] mcp-cli call fails to read JSON from heredoc and file redirection stdin

Description

mcp-cli call <server>/<tool> - fails to parse JSON input when provided via heredoc (<<'EOF') or file redirection (< file.json), but works correctly when piped via cat file.json |.

Steps to Reproduce

Fails — heredoc:

mcp-cli call notion/notion-create-pages - <<'EOF'
{"pages": [{"properties": {"title": "Test"}, "content": "Hello"}]}
EOF

Error: SyntaxError: JSON Parse error: Unexpected EOF

Fails — file redirection:

mcp-cli call notion/notion-create-pages - < /tmp/payload.json

Error: SyntaxError: JSON Parse error: Unexpected EOF

Works — pipe:

cat /tmp/payload.json | mcp-cli call notion/notion-create-pages -

Returns expected result.

The JSON is valid in all cases — the same file content succeeds via pipe.

Expected Behavior

All three stdin methods (heredoc, file redirection, pipe) should work equivalently, as they do for standard Unix tools.

Likely Cause

mcp-cli may be checking for stdin using a method that only detects pipes (e.g., checking process.stdin.isTTY) rather than handling all redirected input sources.

Environment

• Claude Code 2.1.x
• Linux (Ubuntu, kernel 6.8.0)
• Notion MCP server (though likely affects all MCP servers)