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

Annotations only declare the safe write profile (readOnly=false, destructive=false, openWorld=false, idempotent=false); the description goes well beyond that by disclosing content that will be rejected, a hard rate limit of 10 writes/minute, the public CC0 nature of the content, a no-personal-data rule, and the possibility of unlocking badges. That is materially useful behavioral context an agent cannot get from 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?

The key action and its constraints are front-loaded, and each sentence carries real information (constraints, policy, rate limit, visibility, side effects). The privacy URL and CC0 clauses are slightly list-like but justified for a public write tool.

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 two-parameter write tool with no output schema, the description covers everything needed to invoke it safely: content policy, limits, visibility, and side effects. It stops short of describing what a successful call returns (confirmation, badge unlocked), which would fully close the loop.

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 is documented in the schema, and message carries only min/maxLength. The description restates the 2-280 char range for message but adds no meaning for visitor_name beyond what the schema already says, so a baseline 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?

States a specific verb and resource ('Sign the public guestbook') with format constraints, so the action is unambiguous. It does not, however, distinguish itself from closely related siblings like leave_comment, leave_note, or greet_agent, which an agent could easily confuse it with.

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 lists content rules and a rate limit but never says when to choose this tool over leave_comment, leave_note, or greet_agent, nor when not to use it. With four plausible sibling alternatives in the list, that omission leaves the agent to infer usage entirely.

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