# Sign PDF

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

## Tool capabilities

| Property | Value |
| --- | --- |
| Tool ID | `sign-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/sign-pdf/run |
| Browser-agent interface | run_current_tool |

### Implementation notes

Places an uploaded visual signature. This is not certificate-based digital signing. Select the PDF and signature image together.

### Inputs and settings

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

Accepted browser files: `.pdf,.png,.jpg,.jpeg`. Multiple files are supported.

| Setting | Meaning | Control type | Default | Constraints |
| --- | --- | --- | --- | --- |
| `page` | Page | number | 1 |  |
| `x` | X from left (points) | number | 40 |  |
| `y` | Y from bottom (points) | number | 40 |  |
| `width` | Signature width (points) | number | 150 |  |

### 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/sign-pdf/run
Content-Type: application/json
```

[Detailed operation reference](https://happytails.ai/en/api/tools/sign-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": {
        "page": {
          "type": "number",
          "description": "Page",
          "default": 1.0
        },
        "x": {
          "type": "number",
          "description": "X from left (points)",
          "default": 40.0
        },
        "y": {
          "type": "number",
          "description": "Y from bottom (points)",
          "default": 40.0
        },
        "width": {
          "type": "number",
          "description": "Signature width (points)",
          "default": 150.0
        }
      }
    },
    "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

Place drawn/uploaded signatures; explicitly distinguish visual signatures from certificate-based signing.

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

### Complete machine-readable capability record

```json
{
  "id": "sign-pdf",
  "category": "pdf-tools",
  "built": true,
  "requirements": "Place drawn/uploaded signatures; explicitly distinguish visual signatures from certificate-based signing.",
  "implementation": {
    "fields": [
      {
        "key": "page",
        "label": "Page",
        "value": 1,
        "type": "number"
      },
      {
        "key": "x",
        "label": "X from left (points)",
        "value": 40,
        "type": "number"
      },
      {
        "key": "y",
        "label": "Y from bottom (points)",
        "value": 40,
        "type": "number"
      },
      {
        "key": "width",
        "label": "Signature width (points)",
        "value": 150,
        "type": "number"
      }
    ],
    "files": true,
    "multiple": true,
    "input": false,
    "accept": ".pdf,.png,.jpg,.jpeg",
    "note": "Places an uploaded visual signature. This is not certificate-based digital signing. Select the PDF and signature image together.",
    "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/sign-pdf/run",
  "api": {
    "id": "sign-pdf",
    "name": "Sign PDF",
    "category": "pdf-tools",
    "description": "Place a signature image on a PDF page.",
    "notes": "Places an uploaded visual signature. This is not certificate-based digital signing. Select the PDF and signature image together.",
    "human_path": "/en/pdf-tools/sign-pdf/",
    "method": "POST",
    "endpoint": "/api/v1/tools/sign-pdf/run",
    "schema_url": "/api/v1/tools/sign-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": {
            "page": {
              "type": "number",
              "description": "Page",
              "default": 1.0
            },
            "x": {
              "type": "number",
              "description": "X from left (points)",
              "default": 40.0
            },
            "y": {
              "type": "number",
              "description": "Y from bottom (points)",
              "default": 40.0
            },
            "width": {
              "type": "number",
              "description": "Signature width (points)",
              "default": 150.0
            }
          }
        },
        "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

Place a signature image on a PDF page.

## Useful next steps

- [Merge PDF](https://happytails.ai/en/pdf-tools/merge-pdf/): Combine PDF files into one document. ([Markdown](https://happytails.ai/en/pdf-tools/merge-pdf.md))

- [Split PDF](https://happytails.ai/en/pdf-tools/split-pdf/): Save selected PDF pages as separate files. ([Markdown](https://happytails.ai/en/pdf-tools/split-pdf.md))

- [Extract pages](https://happytails.ai/en/pdf-tools/extract-pages/): Create a PDF containing the pages you select. ([Markdown](https://happytails.ai/en/pdf-tools/extract-pages.md))

## How to use Sign PDF

1. Choose one or more files in PDF, PNG or JPEG.
2. Review the settings, then choose Run Sign PDF.
3. Review the result, then use Copy result or a download link when available.

## What to expect

Place a signature image on a PDF page. Choose one PDF and one PNG or JPEG signature image. Set the page, position, and image width in PDF points. This adds a visual signature, not certificate-based digital signing.