REST HTTP Caller Skill

This skill enables you to make HTTP/REST API calls using a simple C# script that runs with dotnet run.

Prerequisites

• .NET 10 or later installed (for dotnet run app.cs support)
• Network access to the target endpoint

Usage

Run the HTTP caller script using dotnet run:

dotnet run HttpCaller.cs -- <METHOD> <URL> [OPTIONS]

Arguments

Argument	Required	Description
METHOD	Yes	HTTP method: GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS
URL	Yes	The full URL to call (must include scheme, e.g., https://)

Options

Option	Description	Example
--header or -H	Add a header (can be used multiple times)	--header "Authorization: Bearer token123"
--body or -b	Request body (JSON string)	--body '{"name": "test"}'
--body-file or -f	Read request body from a file	--body-file request.json
--timeout or -t	Request timeout in seconds (default: 30)	--timeout 60
--output or -o	Save response body to a file	--output response.json
--verbose or -v	Show detailed request/response info	--verbose
--help or -?	Show help and usage information	--help

Examples

GET Request

dotnet run HttpCaller.cs -- GET https://api.example.com/users

GET with Authentication Header

dotnet run HttpCaller.cs -- GET https://api.example.com/users --header "Authorization: Bearer YOUR_TOKEN_HERE"

POST with JSON Body

dotnet run HttpCaller.cs -- POST https://api.example.com/users --header "Content-Type: application/json" --body '{"name": "John Doe", "email": "john@example.com"}'

PUT Request with Body from File

dotnet run HttpCaller.cs -- PUT https://api.example.com/users/123 --header "Content-Type: application/json" --body-file update-user.json

DELETE Request

dotnet run HttpCaller.cs -- DELETE https://api.example.com/users/123 --header "Authorization: Bearer YOUR_TOKEN_HERE"

Multiple Headers

dotnet run HttpCaller.cs -- POST https://api.example.com/data --header "Content-Type: application/json" --header "Authorization: Bearer TOKEN" --header "X-Custom-Header: value" --body '{"data": "test"}'

Verbose Output with Timeout

dotnet run HttpCaller.cs -- GET https://api.example.com/slow-endpoint --timeout 120 --verbose

Save Response to File

dotnet run HttpCaller.cs -- GET https://api.example.com/large-data --output data.json

Script Location

The HTTP caller script is located at: HttpCaller.cs

Output Format

The script outputs:

• Status: HTTP status code and reason phrase
• Headers: Response headers (in verbose mode)
• Body: Response body (JSON is automatically formatted)

Example Output

=== HTTP Response ===
Status: 200 OK

Body:
{
  "id": 123,
  "name": "John Doe",
  "email": "john@example.com"
}

Verbose Output

=== HTTP Request ===
Method: POST
URL: https://api.example.com/users
Headers:
  Content-Type: application/json
  Authorization: Bearer ***
Body:
{"name": "John Doe", "email": "john@example.com"}

=== HTTP Response ===
Status: 201 Created
Headers:
  Content-Type: application/json
  X-Request-Id: abc123
Body:
{
  "id": 456,
  "name": "John Doe",
  "email": "john@example.com"
}

Common Use Cases

1. Testing APIs: Quickly test REST endpoints during development
2. Fetching Data: Retrieve data from external services
3. Automation: Integrate API calls into workflows
4. Debugging: Use verbose mode to inspect request/response details
5. Authentication Testing: Test various auth mechanisms (Bearer, API Key, Basic)

Error Handling

The script provides clear error messages for common issues:

• Network errors
• Invalid URLs
• Timeout errors
• HTTP error status codes (4xx, 5xx)

Tips for LLM Usage

When using this skill, fill in:

1. METHOD: Choose the appropriate HTTP method for the operation
2. URL: Provide the complete endpoint URL
3. Headers: Add necessary headers like Content-Type, Authorization, etc.
4. Body: For POST/PUT/PATCH, provide the request body as JSON

Always include Content-Type: application/json header when sending JSON data.