I am new to endpoints and FastAPI and cannot figure out how to do a POST request.

Here is my code:

public void post(EditText tool, String postURL) {
        RequestBody requestBody = new FormBody.Builder()
                .add("tool_name", "name")
                .add("users", "name")
                .add("availability", "true")
                .add("description", "name")
                .add("visible", "true")
                .build();
        Request request = new Request.Builder().url(postURL).post(requestBody).build();



        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(@NonNull Call call, @NonNull IOException e) {
                e.printStackTrace();
            }

            @Override
            public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            tool.setHint(response.body().string());
                            System.out.println(tool.getHint());
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                });
            }
        });

When I try to run the code, it gives me an error saying:
{"detail":[{"type":"model_attributes_type","loc":["body"],"msg":"Input should be a valid dictionary or object to extract fields from","input":"tool_name=name&users=name&availability=true&description=name&visible=true"}]}

I know I have the endpoint link right and everything.

Here is the Python code for this post endpoint:

@app.post("/tool")
def postTool(tool: Tool):
    tools.append(tool)
    return tools