# List combinations

- Human page: https://happytails.ai/en/text-tools/list-combinations/
- Markdown: https://happytails.ai/en/text-tools/list-combinations.md
- Structured JSON: https://happytails.ai/agents/en/text-tools/list-combinations/index.json
- Visibility: public

## Tool capabilities

| Property | Value |
| --- | --- |
| Tool ID | `list-combinations` |
| Category | text-tools |
| Implementation | Registered implementation. Registration alone is not a production-quality guarantee. |
| Browser execution | Use the visible action or interactive controls. |
| Browser processing | Browser; see tool notes for network behavior. |
| HTTP API | /api/v1/tools/list-combinations/run |
| Browser-agent interface | run_current_tool |

### Implementation notes

One item per line. Separate lists with a blank line. Maximum 10,000 results.

### Inputs and settings

Text input: Lists to combine.

Example or placeholder shown in the interface (not a validated fixture):

```text
A
B

1
2
```

Put one item per line and leave a blank line between lists. Up to 1,000,000 characters. Review the settings before running.

| Setting | Meaning | Control type | Default | Constraints |
| --- | --- | --- | --- | --- |
| `separator` | Join items with | text | " " |  |

### HTTP contract

API calls process supplied data on the server. The website origin is `https://happytails.ai`. Server API hosting is not connected on the public website yet. Use your local server origin to test these requests.

```http
POST https://happytails.ai/api/v1/tools/list-combinations/run
Content-Type: application/json
```

[Detailed operation reference](https://happytails.ai/en/api/tools/list-combinations.md) · [Shared API guide](https://happytails.ai/en/api.md)

#### Limits

| Limit | Value |
| --- | --- |
| request_bytes | 8388608 |
| input_characters | 1000000 |
| files_bytes | 5242880 |
| max_files | 0 |
| timeout_seconds | 12 |

#### Complete input schema

```json
{
  "type": "object",
  "additionalProperties": false,
  "properties": {
    "input": {
      "type": "string",
      "maxLength": 1000000,
      "default": "",
      "description": "Plain text input. File tools use files instead unless otherwise documented."
    },
    "options": {
      "type": "object",
      "additionalProperties": false,
      "properties": {
        "separator": {
          "type": "string",
          "description": "Join items with",
          "default": " "
        }
      }
    }
  }
}
```

#### Complete output schema

```json
{
  "type": "object",
  "required": [
    "tool",
    "result"
  ],
  "properties": {
    "tool": {
      "type": "string"
    },
    "result": {
      "type": "object",
      "required": [
        "text",
        "files"
      ],
      "properties": {
        "text": {
          "type": [
            "string",
            "null"
          ]
        },
        "data": {
          "description": "Parsed JSON when the textual result is JSON."
        },
        "name": {
          "type": "string"
        },
        "mime": {
          "type": "string"
        },
        "files": {
          "type": "array",
          "items": {
            "type": "object",
            "required": [
              "name",
              "mime",
              "bytes",
              "base64"
            ],
            "properties": {
              "name": {
                "type": "string"
              },
              "mime": {
                "type": "string"
              },
              "bytes": {
                "type": "integer"
              },
              "base64": {
                "type": "string",
                "contentEncoding": "base64"
              }
            }
          }
        }
      }
    }
  }
}
```

#### Recorded request and response

Saved fixture from 2026-09-28T18:13:36Z. This is historical evidence, not a new validation or a guarantee for every input.

```json
{
  "input": "A\nB\n\n1\n2",
  "options": {}
}
```

```json
{
  "tool": "list-combinations",
  "result": {
    "text": "A 1\nA 2\nB 1\nB 2",
    "files": [],
    "name": "result.txt",
    "mime": "text/plain;charset=utf-8"
  }
}
```

#### Error and retry handling

Failures return a non-200 status and `error.code` plus `error.message`. Correct invalid input before retrying; retry server-busy responses with bounded backoff. Returned files contain Base64 data, not persistent download URLs. Decode and inspect the output before treating conversion as successful. See the shared API guide for the complete status and timeout rules.

### Browser-agent workflow

1. Open the human page in a browser that supports WebMCP.
2. Discover the interface exposed by that page; use its actual schema.
3. Select files on the page first when the tool requires files.
4. Call `run_current_tool` with valid input and settings.
5. Inspect the returned result or error and the displayed output. Retrieve files from the displayed download links.

Calls do not automatically copy or download results. Browser permissions still apply. Interface availability alone is not proof of successful execution.

### Planning specification

Generate the Cartesian product of input lists; preview result count before generation, cap output safely, configure separators and duplicate handling; distinguish combinations from concatenating lines.

This describes intended requirements. Use the implementation notes, interface schema and observed output to determine current support.

### Complete machine-readable capability record

```json
{
  "id": "list-combinations",
  "category": "text-tools",
  "built": true,
  "requirements": "Generate the Cartesian product of input lists; preview result count before generation, cap output safely, configure separators and duplicate handling; distinguish combinations from concatenating lines.",
  "implementation": {
    "fields": [
      {
        "key": "separator",
        "label": "Join items with",
        "value": " ",
        "type": "text"
      }
    ],
    "note": "One item per line. Separate lists with a blank line. Maximum 10,000 results.",
    "experience": {
      "automatic": false,
      "single": false,
      "label": "Lists to combine",
      "placeholder": "A\nB\n\n1\n2",
      "help": "Put one item per line and leave a blank line between lists. Up to 1,000,000 characters. Review the settings before running.",
      "action": null
    },
    "mode": "explicit",
    "interactive": false
  },
  "execution": "POST /api/v1/tools/list-combinations/run",
  "api": {
    "id": "list-combinations",
    "name": "List combinations",
    "category": "text-tools",
    "description": "Generate every combination from groups of items.",
    "notes": "One item per line. Separate lists with a blank line. Maximum 10,000 results.",
    "human_path": "/en/text-tools/list-combinations/",
    "method": "POST",
    "endpoint": "/api/v1/tools/list-combinations/run",
    "schema_url": "/api/v1/tools/list-combinations",
    "input_schema": {
      "type": "object",
      "additionalProperties": false,
      "properties": {
        "input": {
          "type": "string",
          "maxLength": 1000000,
          "default": "",
          "description": "Plain text input. File tools use files instead unless otherwise documented."
        },
        "options": {
          "type": "object",
          "additionalProperties": false,
          "properties": {
            "separator": {
              "type": "string",
              "description": "Join items with",
              "default": " "
            }
          }
        }
      }
    },
    "output_schema": {
      "type": "object",
      "required": [
        "tool",
        "result"
      ],
      "properties": {
        "tool": {
          "type": "string"
        },
        "result": {
          "type": "object",
          "required": [
            "text",
            "files"
          ],
          "properties": {
            "text": {
              "type": [
                "string",
                "null"
              ]
            },
            "data": {
              "description": "Parsed JSON when the textual result is JSON."
            },
            "name": {
              "type": "string"
            },
            "mime": {
              "type": "string"
            },
            "files": {
              "type": "array",
              "items": {
                "type": "object",
                "required": [
                  "name",
                  "mime",
                  "bytes",
                  "base64"
                ],
                "properties": {
                  "name": {
                    "type": "string"
                  },
                  "mime": {
                    "type": "string"
                  },
                  "bytes": {
                    "type": "integer"
                  },
                  "base64": {
                    "type": "string",
                    "contentEncoding": "base64"
                  }
                }
              }
            }
          }
        }
      }
    },
    "processing": "Server; same transformation code as browser tools",
    "limits": {
      "request_bytes": 8388608,
      "input_characters": 1000000,
      "files_bytes": 5242880,
      "max_files": 0,
      "timeout_seconds": 12
    }
  },
  "agent_processing": "Server; same transformation code as browser tools",
  "browser_agent": {
    "supported": true,
    "name": "run_current_tool",
    "discovery": "WebMCP on the human page in a supporting browser",
    "verification": "See audit/API-AUDIT.md; availability is not verification"
  }
}
```

## Page guide

Generate every combination from groups of items.

## How to use List combinations

1. Enter lists to combine in the input field.
2. Review the settings, then choose Run List combinations.
3. Review the result, then use Copy result or a download link when available.

## What to expect

Generate every combination from groups of items. Put one item on each line and a blank line between groups. Output is limited to 10,000 combinations.

### Try a small example

```
A
B

1
2
```

## Useful next steps

- [Split text](https://happytails.ai/en/text-tools/split-text/): Split text at an exact separator, placing each part on a new line. ([Markdown](https://happytails.ai/en/text-tools/split-text.md))

- [Join text](https://happytails.ai/en/text-tools/join-text/): Join lines with a separator of your choice. ([Markdown](https://happytails.ai/en/text-tools/join-text.md))

- [Comma separated list](https://happytails.ai/en/text-tools/comma-separated-list/): Turn nonempty lines into a comma-separated list. ([Markdown](https://happytails.ai/en/text-tools/comma-separated-list.md))

- [Add prefix suffix](https://happytails.ai/en/text-tools/add-prefix-suffix/): Add a prefix or suffix to every line. ([Markdown](https://happytails.ai/en/text-tools/add-prefix-suffix.md))