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

Annotations already declare readOnlyHint=false and destructiveHint=false, and the description usefully adds that it returns a result file rather than modifying in place. However, it does not address permissions, whether the original is altered, processing limits (only in schema), or anything about the produced output beyond its existence.

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?

Two short, front-loaded sentences with no filler; the operation is stated first and the return behavior second. Every clause carries information an agent can act on.

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?

For a simple two-parameter tool with fully documented nested schema and no output schema, the description covers purpose and return shape adequately. The only meaningful gap is the misleading 'every page' generalization against the pages option, which the schema resolves.

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 100%, so the schema carries the parameter semantics, and the description adds essentially nothing beyond the text example. Critically, the phrase 'on every page' contradicts the presence of a 'pages' option that scopes the watermark, and options like layout, opacity, color and size go unmentioned.

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 gives a specific verb and resource ('Stamp text ... on every page') plus concrete examples ('CONFIDENTIAL', 'DRAFT') that make the operation immediately recognizable. It is reasonably distinguishable from siblings like add-page-numbers or protect-pdf, though it never names an alternative to sharpen that distinction.

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?

Usage is only implied by the examples of watermark text; there is no explicit when-to-use, when-not-to-use, or pointer to a related tool such as add-page-numbers or protect-pdf. An agent can infer the purpose but gets no routing help.

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