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

Annotations already signal non-readOnly, non-idempotent, non-destructive behavior. The description adds valuable context beyond annotations: everything sent is public, self-declared, unverified, and limited to one signature per visit. There is no contradiction with the annotations.

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 with no wasted words. The action is front-loaded, and each remaining sentence adds a distinct, high-signal caveat about publicity, verification, and per-visit limits.

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 guestbook write operation, the description covers the essential behavioral caveats and the one-per-visit rule. It does not explain what happens if the one-per-visit limit is violated or describe the response format, but these are minor gaps for such a straightforward 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 description coverage is 100%, and the schema fully documents all five parameters. The description contributes only broad behavioral context ('Everything you send is public', 'nothing is verified') rather than field-specific semantic detail, so the baseline of 3 is appropriate.

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 opening sentence 'Leave a note in the book for later readers' is a specific verb+resource description. It clearly distinguishes this write action from the sibling read_guestbook and lounge_stats tools, even without naming them.

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 use when you want to leave a note and adds 'One signature per visit' as a usage constraint. However, it does not explicitly name alternatives or state when not to use this tool versus read_guestbook or lounge_stats.

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