Why can’t I use strtok directly on a string in C, and why do I need to copy it first?

I don’t understand why I can’t directly strtok(argv[1], ";")

(whould there be a difference if the argv[1] is indeed an input from terminal with argv[1] is actually a list on heap?)

    char *multiDecimalToBinary(char *argv[], int count) {
         int maxLen = 80 * (count + 1); // Max memory needed for result in this situation
        char *result = malloc(maxLen * sizeof(char));
        if (result == NULL) {
            return NULL;
        }
        result[0] = '\0'; // Initialize the result string


    /// why I need to copy argv[1] here?
    /// I think if run through terminal, argv might be an static val,
    /// but during the test, I pass in char *test = malloc(...)
        char *s = malloc((strlen(argv[1]) + 1) * sizeof(char));
        strcpy(s, argv[1]);
        char *type = strtok(s, ";");

    //    printf("%s\n",argv[1]);
    //    char *type = strtok(argv[1], ";");
    //    printf("here\n");

    void testMultiDecimalToBinary(void) {
        char **test = malloc(5 * sizeof(char *));

        test[1] = "{char;int;unsigned char}";
        test[2] = "7";
        test[3] = "10000000";
        test[4] = "255";
        assert(strcmp(multiDecimalToBinary(test, 2),
        "0000 0111 0000 0000 1001 1000 1001 0110 1000 0000 1111 1111") == 0);

        free(test);
    }

I thought both of this two method should work, but only one can

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