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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world scope, so safety is covered. The description adds genuinely new behavioral context: the tool fails for three specific book types and returns a single-person link rather than a group one. It does not say what the failure looks like (error vs. null) or anything about link lifetime, which keeps it from a 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 short sentences, front-loaded with what is returned before the refusal conditions. Every sentence carries information about the return value, exclusions, or the alternative. Minor awkwardness ('an as they grow book') slightly hurts readability but not substance.

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 one-parameter read-only link getter with annotations covering safety and no output schema, the description covers what is returned, who it is for, and when it fails. The remaining gap is what the returned link looks like or whether it expires, which is minor for this complexity level.

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 is one parameter with 100% schema description coverage ('The book's handle'), so the schema already carries parameter meaning. The description adds no syntax, handle format, or lookup guidance beyond that. Baseline 3 is appropriate for full schema coverage with no extra param insight.

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 names a specific return value (the second link) and explains what that link does: it puts questions to the person the book is about regarding their own life. It also distinguishes it from the 'collecting link' used for group chats, which separates it from the family of link-related siblings. The phrase 'second link' is mildly jargon-dependent, and it never explicitly names the get_links sibling, keeping it just short of a 5.

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?

It gives concrete when-not conditions: refuses on a memorial, a new baby book, and an 'as they grow' book, where the person cannot answer. It also states the alternative for the group-chat case, pointing to the collecting link. There is no explicit naming of the sibling tool that returns the collecting link, so the routing is conceptual rather than literal.

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