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

With no annotations, the description carries the full burden and does well: it discloses that pinned pages are scanned in every site scan, count toward the score, are capped at 25 on the site, and that changes apply from the next scan. It also notes the return shape. It does not mention auth/permissions or reversibility of pinning, keeping it short of 5.

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 front-loaded sentences with zero filler; the core action, the 25-pin cap, and the delayed-effect caveat each earn their place.

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?

Despite no output schema and no annotations, the description covers scope, limits, timing of effect, and return contents ('each address's outcome and the pins now in place'), which is everything an agent needs to call it correctly.

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%, so pin, unpin, and host are already documented with types, bounds, and constraints. The description adds only that both lists may be supplied together, which is marginal beyond the schema; baseline 3 applies.

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 (pin or unpin) and resource (pages) plus scope (on one of the signed-in person's sites). No sibling tool touches pinning, so it is unambiguous and distinguishable from the scan/report siblings.

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?

Instructs to 'give pin and/or unpin lists' and that addresses must be on the site, which implies how to call it. However, it gives no explicit when-to-use vs when-not context or prerequisites (e.g., needing a scan first, permissions), and there is no named alternative.

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