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

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=true, so the safety profile is covered. The description adds the AES-256 encryption detail, which is useful behavioral context. However, it does not disclose what happens to the original file, whether the output is a new file, or whether the password is returned in the response.

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 sentence that is front-loaded with the action and resource, and it includes the encryption detail without any waste. Every word earns its place.

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?

The tool has a simple two-parameter schema with 100% coverage and an output schema, so the description does not need to explain return values. The only minor gap is that it does not mention whether the original file is modified or a new protected file is produced, but the annotations and schema cover most of what an agent needs.

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 already documents both parameters. The description adds no additional meaning beyond what the schema provides, but it does not need to since the schema is complete. Baseline 3 is appropriate.

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 ('Protect'), a resource ('a PDF'), and the method ('password (AES-256 encryption)'). It clearly distinguishes this from siblings like unlock_pdf and compress_pdf, so an agent can tell what the tool 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.

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

The description implies the tool is for adding password protection to a PDF, and the sibling list includes unlock_pdf, which suggests the alternative for removing protection. However, it does not explicitly state when to use this tool versus alternatives, nor does it mention any prerequisites or limitations (e.g., only works on PDFs, password strength requirements).

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