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

Annotations only declare readOnly, non-idempotent, non-destructive, and closed-world. The description adds meaningful behavior beyond that: cryptographic security, the guarantee that each enabled set appears at least once, shuffling, one password per line, fresh output every call, and that passwords are neither stored nor logged.

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?

Four dense sentences with no filler. The core action, guarantees, output format, and error condition are all front-loaded and easy to scan.

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 no output schema, the description still explains the return shape ('one password per line') and the failure mode. For a six-parameter generator, nothing an agent needs to invoke it correctly 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 coverage is 100%, so parameter documentation already exists. The description still adds cross-parameter semantics the schema lacks, specifically the at-least-once guarantee per enabled character set and the all-sets-disabled error condition.

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 and resource ('Generate random passwords') and pins the implementation to a cryptographically secure generator. It is clearly distinct from siblings such as generate_uuid, hash_text, and base64, which also produce strings but for different purposes.

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?

Gives clear operating context: every call yields new results, and an error occurs if all character sets are disabled. It does not explicitly name alternatives or when not to use it, but the purpose is narrow enough that little inference is required.

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