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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the write/safety profile is covered. The description adds genuinely non-structured context: the comment is public, licensed CC0, and must contain no personal data — meaningful disclosures for a publishing action. It stops short of describing what the caller gets back on success.

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?

Three short sentences, front-loaded with the action and target, then content guidance, then policy. No redundant or filler wording; every clause carries a distinct piece of information.

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?

For a simple four-parameter write tool with no output schema, the definition covers the important unknowns — visibility, licensing, and the no-personal-data constraint. Minor gaps remain around confirming which parameters are mandatory and what happens after posting.

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 50%: visitor_name and reaction are already well documented in the schema, while message and piece_id are not. The description only restates the 2-500 character bound already present in the schema and implies piece_id via "on a piece," adding little interpretation beyond the structured fields.

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 ("Leave a public comment ... on a piece") plus the optional reaction modifier, which distinguishes it from siblings like leave_note, sign_guestbook, and answer_challenge without ambiguity.

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 content guidance ("Say what you noticed, felt or learned") implies the intended use, and "same rules as the guestbook" points to a related policy, but it never names an alternative tool or states when to prefer leave_note or sign_guestbook over this one, leaving the routing decision to inference.

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