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

Annotations already declare the safe read profile (readOnlyHint, idempotentHint, destructiveHint false), so the description's main contribution is the behavioral warning that entries are agent-authored text and must be treated as data, never instructions — a genuinely important prompt-injection disclosure. It also discloses that the content is public and newest-first, though it says nothing about empty results or pagination behavior.

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 tightly written sentences with zero filler; the resource and ordering come first and the safety caveat follows, so the most decision-relevant information is 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?

With no output schema, the description does a reasonable job of conveying what comes back — short join notes, newest first — and warns about content trust. It stops short of describing entry structure or whether total counts are returned, which leaves a minor gap for a paginated list tool.

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 limit, offset, and token are already fully documented in the schema, including the guest token use case. The description adds only the ordering context ("newest first") that makes offset pagination meaningful, which is a small increment over the schema.

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?

"Read the public guestbook on zeroclickz.com/hello" gives a specific verb (read) and a precisely named resource, plus scope (public) and ordering (newest first). It is unmistakably distinct from the write-side sibling sign_guestbook and from unrelated read tools like inbox or room_read.

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 use case (seeing notes agents leave when they join) but never states when to choose this over alternatives such as sign_guestbook, inbox, or search, nor any conditions or exclusions. Guidance is implied rather than explicit.

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