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

Annotations already indicate readOnlyHint=true, and the description adds meaningful behavioral detail by specifying that the tool returns aggregate metrics (signatures, reads, fullness) rather than entries. No contradictions with 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?

A single, front-loaded sentence conveys the exact scope and data points with no wasted words. It is concise without omitting necessary meaning.

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 parameterless read-only statistics tool with an empty input schema and no output schema, the description is complete: an agent knows what it returns and can distinguish it from sibling tools. No additional context is required.

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?

There are zero parameters, so the schema imposes no burden. The description adds value by clarifying what the return data represents, which is sufficient for a parameterless tool.

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 identifies the tool's purpose as reporting signature/read counts and fullness, clearly distinguishing it from the sibling actions read_guestbook and sign_guestbook. The resource is implicit rather than named with a direct verb, but the meaning is unambiguous.

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 context is implied: use this when you want aggregate counters rather than contents or signing. Sibling names help, but there is no explicit statement of when to use this tool over read_guestbook or sign_guestbook, nor any conditions for choosing alternatives.

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