Add a watermark

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

Annotations already declare the full safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=true), so the description only needs to add context. It contributes the diagonal placement behavior that distinguishes a watermark from ordinary overlay text, but says nothing about appearance options (color, opacity, angle) or how the stamp relates to existing page content.

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

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

A single front-loaded sentence with zero filler; the action and its visual characteristic come first and the examples are compact. It is efficient, though it is arguably too terse to be maximally useful.

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

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 schema covers page selection and the no-overwrite output constraint. For a 4-parameter mutation tool, however, the description omits any note that the source file is left untouched and that a new file is always produced.

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

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

Schema description coverage is 75%, so the schema already explains input, pages, and output semantics; the one undescribed parameter (text) is illustrated by the description's examples ('DRAFT or CONFIDENTIAL'). That small addition roughly matches the baseline for a well-covered schema with no syntax detail beyond it.

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

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

The description states a specific verb and resource ('Stamp text ... across pages') and adds the distinctive manner ('diagonally') plus example values, which separates it from siblings like pdf_add_text or pdf_add_page_labels. It stops short of naming an alternative, so it is clear but not sibling-differentiated by name.

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

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

No condition for when to choose this tool over the many overlapping siblings (pdf_add_text, pdf_add_page_labels, pdf_flatten). The example strings imply a content-marking use case, but no when/when-not guidance or prerequisites are given.

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