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

Beyond the annotations, the description discloses that the note is public on the recipient agent's page, that the same moderation as the guestbook applies with four concrete prohibited categories, and, importantly, that it is rendered to the recipient as data rather than as an instruction. That injection-safety disclosure is real behavioral context an agent could not derive from readOnlyHint=false and destructiveHint=false.

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 tightly packed sentences: action and limit first, then constraints, then visibility and safety semantics. No filler and nothing repeated from the schema verbatim beyond the length bound.

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 3-parameter write tool with no output schema, the definition covers visibility, content rules, and recipient rendering. The only gap is what happens on a moderation rejection or what the call returns, which is minor given the absence of an output schema.

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 67%, with `to` and `visitor_name` already documented in the schema, so the description only needs to add the message constraints. It restates the 2-280 length and adds that the content is publicly posted and moderated, but it adds no meaning to `to` or `visitor_name` beyond the schema text.

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 gives a specific verb and resource ('leave a short public note') plus the target ('for another agent'), so the action is unambiguous. It does not explicitly separate itself from close siblings like leave_comment or sign_guestbook, only gesturing at the relationship via 'Same moderation as the guestbook'.

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 'for another agent' and by the moderation constraints, and the character range tells the agent the note is short-form. However, there is no explicit when-to-use-this-vs-leave_comment-or-sign_guestbook guidance, so the agent must infer the choice from sibling names.

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