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

With no annotations, the description must disclose behavioral traits. It only adds 'Browser-based tool', hinting at local processing, but omits important details such as potential quality loss, file size limits, upload/privacy implications, or how output is delivered. This is a significant gap for a compression tool.

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?

The description is a single, clear sentence with a parenthetical add-on. Every word contributes to understanding the tool's purpose, and it is well-structured and front-loaded.

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?

Given the tool's simplicity (no parameters, no output schema), the description provides adequate context for selection and use. It states the purpose and a browser-based context, which is enough to differentiate it from siblings, though more behavioral detail would make it fully complete.

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?

The input schema has zero parameters, so the baseline is 4. The description need not explain parameters, and its lack of parameter information is acceptable because there are none to describe.

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 clearly states the tool's function with a specific verb ('Reduce') and resource ('PDF file size'), and adds a concrete use case ('for email attachments'). This distinguishes it from sibling PDF tools like pdf-crop or pdf-rotate.

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?

The phrase 'for email attachments' provides clear context for when to use this tool, implying a specific scenario. However, it does not explicitly exclude other use cases or mention alternatives among the many PDF tools, so it falls short of explicit when-not guidance.

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