# Alternate merge PDF

- Human page: https://happytails.ai/en/pdf-tools/alternate-merge-pdf/
- Markdown: https://happytails.ai/en/pdf-tools/alternate-merge-pdf.md
- Structured JSON: https://happytails.ai/agents/en/pdf-tools/alternate-merge-pdf/index.json
- Visibility: public

## Tool capabilities

| Property | Value |
| --- | --- |
| Tool ID | `alternate-merge-pdf` |
| Category | pdf-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/alternate-merge-pdf/run |
| Browser-agent interface | run_current_tool |

### Implementation notes

Runs on your device. Up to 100 pages per input. Choose front scans first, back scans second. Extra pages are appended in order.

### Inputs and settings

No free-text input is required. Use the file inputs and/or settings below.

Accepted browser files: `.pdf`. Multiple files are supported.

| Setting | Meaning | Control type | Default | Constraints |
| --- | --- | --- | --- | --- |
| `reverse` | Reverse the second PDF (back scans) | checkbox | false |  |

### 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/alternate-merge-pdf/run
Content-Type: application/json
```

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

#### Limits

| Limit | Value |
| --- | --- |
| request_bytes | 8388608 |
| input_characters | 1000000 |
| files_bytes | 5242880 |
| max_files | 20 |
| 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": {
        "reverse": {
          "type": "boolean",
          "description": "Reverse the second PDF (back scans)",
          "default": false
        }
      }
    },
    "files": {
      "type": "array",
      "maxItems": 20,
      "items": {
        "type": "object",
        "required": [
          "name",
          "base64"
        ],
        "additionalProperties": false,
        "properties": {
          "name": {
            "type": "string",
            "maxLength": 200,
            "description": "Filename only, no path."
          },
          "mime": {
            "type": "string",
            "maxLength": 150
          },
          "bytes": {
            "type": "integer",
            "minimum": 0,
            "description": "Optional decoded byte count; must match content if supplied."
          },
          "base64": {
            "type": "string",
            "contentEncoding": "base64",
            "description": "File bytes as padded base64. Use the tool-specific limits.files_bytes value for the total decoded input size."
          }
        }
      }
    }
  }
}
```

#### 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"
              }
            }
          }
        }
      }
    }
  }
}
```

#### 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

Exactly two PDFs; optionally reverse second document; append unmatched pages; keep text selectable.

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

### Complete machine-readable capability record

```json
{
  "id": "alternate-merge-pdf",
  "category": "pdf-tools",
  "built": true,
  "requirements": "Exactly two PDFs; optionally reverse second document; append unmatched pages; keep text selectable.",
  "implementation": {
    "fields": [
      {
        "key": "reverse",
        "label": "Reverse the second PDF (back scans)",
        "value": false,
        "type": "checkbox"
      }
    ],
    "files": true,
    "input": false,
    "multiple": true,
    "accept": ".pdf",
    "note": "Runs on your device. Up to 100 pages per input. Choose front scans first, back scans second. Extra pages are appended in order.",
    "experience": {
      "automatic": false,
      "single": false,
      "label": "Your text",
      "placeholder": "Type or paste your input…",
      "help": "Up to 1,000,000 characters. Review the settings before running.",
      "action": null
    },
    "mode": "explicit",
    "interactive": false
  },
  "execution": "POST /api/v1/tools/alternate-merge-pdf/run",
  "api": {
    "id": "alternate-merge-pdf",
    "name": "Alternate merge PDF",
    "category": "pdf-tools",
    "description": "Combine front and back scans in alternating order.",
    "notes": "Runs on your device. Up to 100 pages per input. Choose front scans first, back scans second. Extra pages are appended in order.",
    "human_path": "/en/pdf-tools/alternate-merge-pdf/",
    "method": "POST",
    "endpoint": "/api/v1/tools/alternate-merge-pdf/run",
    "schema_url": "/api/v1/tools/alternate-merge-pdf",
    "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": {
            "reverse": {
              "type": "boolean",
              "description": "Reverse the second PDF (back scans)",
              "default": false
            }
          }
        },
        "files": {
          "type": "array",
          "maxItems": 20,
          "items": {
            "type": "object",
            "required": [
              "name",
              "base64"
            ],
            "additionalProperties": false,
            "properties": {
              "name": {
                "type": "string",
                "maxLength": 200,
                "description": "Filename only, no path."
              },
              "mime": {
                "type": "string",
                "maxLength": 150
              },
              "bytes": {
                "type": "integer",
                "minimum": 0,
                "description": "Optional decoded byte count; must match content if supplied."
              },
              "base64": {
                "type": "string",
                "contentEncoding": "base64",
                "description": "File bytes as padded base64. Use the tool-specific limits.files_bytes value for the total decoded input size."
              }
            }
          }
        }
      }
    },
    "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": 20,
      "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

Combine front and back scans in alternating order.

## Useful next steps

- [Split PDF in half](https://happytails.ai/en/pdf-tools/split-pdf-in-half/): Split scanned spreads into two pages. ([Markdown](https://happytails.ai/en/pdf-tools/split-pdf-in-half.md))

- [Bates number PDF](https://happytails.ai/en/pdf-tools/bates-number-pdf/): Add a unique reference number to every PDF page. ([Markdown](https://happytails.ai/en/pdf-tools/bates-number-pdf.md))

- [PDF header footer](https://happytails.ai/en/pdf-tools/pdf-header-footer/): Add a header and footer to every PDF page. ([Markdown](https://happytails.ai/en/pdf-tools/pdf-header-footer.md))

## How to use Alternate merge PDF

1. Choose the front-scan PDF, then the back-scan PDF.
2. Review the clearly labeled settings. Choose the action button to process your file.
3. Compare the result with your original, then download it. Keep the original for further edits.

## What to expect

Combine front and back scans in alternating order. Exactly two PDFs; optionally reverse second document; append unmatched pages; keep text selectable.