<?xml version="1.0"?>
    <routes xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Webapi:etc/webapi.xsd">
        <route url="/V1/hello/name/:name" method="GET">
            <service class="InchooHelloApiHelloInterface" method="name"/>
            <resources>
                <resource ref="anonymous"/>
            </resources>
        </route>
        <route url="/V1/hello/test/:test" method="POST">
            <service class="InchooHelloApiTestInterface" method="test"/>
            <resources>
                <resource ref="anonymous"/>
            </resources>
        </route>
    </routes>

<?php
namespace InchooHelloApi;

interface TestInterface
{
    /**
     * Returns greeting message to user
     *
     * @api
     * @param id $name Users id.
     * @return id Greeting message with users id.
     */
    public function test($id);
}

<?php
namespace InchooHelloModel;
use InchooHelloApiTestInterface;

class Test implements TestInterface
{
    /**
     * Returns greeting message to user
     *
     * @api
     * @param string $name Users name.
     * @return string Greeting message with users name.
     */
    public function test($id) {
        return "Hello How are you your id is:," .$id;
    }
}

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <preference for="InchooHelloApiHelloInterface" type="InchooHelloModelHello" />
    <preference for="InchooHelloApiTestInterface" type="InchooHelloModelTest" />
</config>