Password-protect a PDF

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

Goes well beyond the annotations (readOnlyHint=false, idempotentHint=false, destructiveHint=false) by disclosing that the password is used locally and never transmitted, that it is unrecoverable and must be stored safely, and that the file is read and written entirely on this machine. This is exactly the behavioral context an agent needs for a security-sensitive mutation.

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?

Front-loaded with the core action and its consequence, and each sentence carries weight. Slight redundancy between 'never transmitted' and 'never sent anywhere' costs it the top score.

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?

With 7 params fully documented in the schema and annotations covering the mutation profile, the description supplies the missing security/locality context and needs no return-value documentation. It could say a bit more about overwrite behavior or the durability of the restriction flags, but nothing essential is missing.

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 baseline is 3, but the description adds real meaning for the critical password parameter (used locally, never transmitted, unrecoverable) and pins the encryption strength. It does not clarify the interaction of the restriction flags (noCopy/noPrint/noModify) with the encryption, which the schema already documents individually.

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?

States a specific verb (encrypt / password-protect) and resource (PDF) plus the concrete outcome: the file cannot be opened without the password. An agent can immediately distinguish it from the inverse sibling pdf_unlock.

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 implied by the stated outcome, and it usefully notes that only AES-256 is offered while 40/128-bit are considered weak, which guides the choice of algorithm. However, it never explicitly says when to pick this over alternatives or names the counterpart tool (pdf_unlock) for removing protection.

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