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add_watermark

DestructiveIdempotent

Add text or image watermarks to PDF pages to mark documents as confidential, draft, or approved. Control placement, opacity, rotation, color, and whether the watermark sits above or below content.

Instructions

Add a text watermark ("CONFIDENTIAL", "DRAFT") or an image (a logo) to pages.

position: center (default) or top-/bottom- left/center/right; a corner with opacity=1 makes a stamp such as "APPROVED". opacity 0-1 (default 0.2); rotation in degrees (default 45 at the center, 0 elsewhere); font_size auto-fits if omitted; scale is the image width as a share of the page. color: #rrggbb, black, gray, red, blue, green. layer: over (default) or under the content. Text is Latin characters only. Needs the owner password if the PDF forbids changes. Signed PDFs are refused.

Any password argument can be "ask": the user then types it on a local page, so it never passes through the chat.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "input_path": "<input_path>"
    },
    "name": "add_watermark"
  }
}

Input Schema

Name	Required	Default
`text`	No
`color`	No	gray
`layer`	No	over
`pages`	No
`scale`	No
`opacity`	No
`password`	No
`position`	No	center
`rotation`	No
`font_size`	No
`overwrite`	No
`image_path`	No
`input_path`	Yes
`output_path`	No

Output Schema

Name	Required	Description	Default
`pages`	Yes
`output`	Yes
`password_protected`	Yes
`user_password_changed`	Yes
`permissions_restricted`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Addedv0.1.1Nov 12, 2026

TDQS

A4/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations declare destructiveHint=true and idempotentHint=true, and the description adds real context on top: the owner-password requirement for locked PDFs, refusal of signed PDFs, and the Latin-only limitation on text. It omits whether the operation writes in place or to output_path when overwrite is unset, which is the main remaining behavioral gap for a destructive write.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core action, then packed with parameter facts in short clauses; almost every sentence carries information. The dense semicolon-and-parenthetical style and the mid-sentence line break make it slightly harder to scan than it needs to be, but there is little waste.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return values need no explanation, and the description covers the dominant visual parameters and the password/security behaviors for a 14-parameter destructive tool. Missing are the page-selection syntax and the overwrite/output_path semantics, which an agent would still have to guess.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description carries the full burden and largely meets it: it defines position values, opacity range and default, rotation defaults per position, font_size auto-fit, scale as image width share, color formats, and layer. It leaves pages (page-range syntax), output_path, overwrite, and input_path undocumented, so several of the 14 parameters still have no semantics anywhere.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource: 'Add a text watermark ... or an image ... to pages', immediately clarifying the two content modes. It does not name or distinguish itself from adjacent tools like add_page_numbers or add_comments, but the resource ('watermark') is specific enough that an agent can tell what it does without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives concrete usage recipes and constraints rather than bare description: a corner plus opacity=1 produces a stamp such as 'APPROVED', signed PDFs are refused, and the owner password is needed if changes are forbidden. It stops short of explicitly routing the agent away from alternatives (e.g. add_page_numbers for numbering), so there are no named exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.