Control-agent accept almost anything as correct config while using config-set and config-test commands, it's just need to be proper JSON.

send:

{'arguments': {'Control-agent': {'AaAASDASDAsd': 'oijsadoeifbias'}},
 'command': 'config-set'}

response:

  {
    "result": 0,
    "text": "Configuration applied successfully."
  }

send:

{'arguments': {'Control-agent': {'control-sockets': {'dhcp6': {'socket-name': '/tmp/control_socket',
                                                               'socket-type': 'SOMETHING'}},
                                 'hooks-libraries': [],
                                 'http-host': '192.168.50.252',
                                 'http-port': 8000,
                                 'reverse-ddns': {}}},
 'command': 'config-test'}

response:

  {
    "result": 0,
    "text": "Configuration check successful"
  }

Kea configuration file:

{
    "Control-agent": {
        "control-sockets": {
            "dhcp6": {
                "socket-name": "/home/wlodek/installed/git/var/run/kea/control_socket", 
                "socket-type": "unix"
            }
        }, 
        "http-host": "192.168.50.252", 
        "http-port": 8000
    }
}

Kea/OS versions:

sbin/kea-ctrl-agent -V
1.7.0-git
git f07587f8c62ac1f431487cf591b2b38d08f1303f

lsb_release -a
No LSB modules are available.
Distributor ID:	Debian
Description:	Debian GNU/Linux 9.11 (stretch)
Release:	9.11
Codename:	stretch

       Kea source configure results:
    -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Package:
  Name:              kea
  Version:           1.7.0-git
  Extended version:  1.7.0-git (git f07587f8c62ac1f431487cf591b2b38d08f1303f)
  OS Family:         Linux

  Prefix:            /home/wlodek/installed/git
  Hooks directory:   /home/wlodek/installed/git/lib/kea/hooks
  Premium hooks:     yes
  Included Hooks:    forensic_log flex_id host_cmds subnet_cmds radius host_cache class_cmds cb_cmds

C++ Compiler:
  CXX:             ccache g++
  CXX_VERSION:     g++ (Debian 6.3.0-18+deb9u1) 6.3.0 20170516
  CXX_STANDARD:    201402
  DEFS:            -DHAVE_CONFIG_H
  CPPFLAGS:         -DOS_LINUX 
  CXXFLAGS:        -g -O2
  LDFLAGS:          -lpthread
  KEA_CXXFLAGS:     -Wall -Wextra -Wnon-virtual-dtor -Wwrite-strings -Woverloaded-virtual -Wno-sign-compare -pthread -Wno-missing-field-initializers -fPIC

Python:
  PYTHON:          /usr/bin/python3
  PYTHON_VERSION:  3.5

Boost:
  BOOST_VERSION:   1.62
  BOOST_INCLUDES:  
  BOOST_LIBS:       -lboost_system

OpenSSL:
  CRYPTO_VERSION:  OpenSSL 1.0.2s  28 May 2019
  CRYPTO_CFLAGS:   
  CRYPTO_INCLUDES: 
  CRYPTO_LDFLAGS:  
  CRYPTO_LIBS:     -lcrypto

Botan: no

Log4cplus:
  LOG4CPLUS_VERSION:  1.1.2
  LOG4CPLUS_INCLUDES: -I/usr/include
  LOG4CPLUS_LIBS:     -L/usr/lib -llog4cplus

Flex/bison:
  FLEX:  flex
  BISON: /usr/bin/bison

MySQL:
  MYSQL_VERSION:   10.1.38
  MYSQL_CPPFLAGS:  -I/usr/include/mysql 
  MYSQL_LIBS:      -L/usr/lib/x86_64-linux-gnu  -lmariadbclient -lpthread -lz -lm -ldl -lcrypto

PostgreSQL:
  PGSQL_VERSION:   PostgreSQL 9.6.15
  PGSQL_CPPFLAGS:  -Wdate-time -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -I/usr/include/libxml2 -I/usr/include/tcl8.6 -I/usr/include/postgresql -I/usr/include/postgresql/9.6/server
  PGSQL_LIBS:      -L/usr/lib/x86_64-linux-gnu -lpq

Cassandra CQL:
  no

Sysrepo:
  SYSREPO_VERSION:     0.7.8
  SYSREPO_CPPFLAGS:    -I/usr/local/include    
  SYSREPO_LIBS:        -L/usr/local/lib -lsysrepo   -L/usr/local/lib -lSysrepo-cpp  
  SYSREPO_REPO:        /etc/sysrepo

Google Test:
  no

Google Benchmark:
  no

FreeRADIUS client:
  FREERADIUS_INCLUDE:    -I/usr/local/include
  FREERADIUS_LIB:        -L/usr/local/lib -lfreeradius-client
  FREERADIUS_DICTIONARY: /usr/local/etc/radiusclient/dictionary

Developer:
  Enable Debugging:          no
  Google Tests:              no
  Google Benchmark:          no
  Valgrind:                  found
  C++ Code Coverage:         no
  Logger checks:             no
  Generate Documentation:    no
  Generate Parser:           no
  Generate Messages Files:   no
  Perfdhcp:                  yes
  Kea-shell:                 yes, install to ${prefix}/lib/python3.5/site-packages