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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile needs no restating. Beyond that, the description discloses the non-obvious dual-mode behavior driven by folderId, which is a real trait an agent could not read off the annotations or schema. It stops short of covering pagination, ordering, or whether results are truncated.

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?

Two short sentences, front-loaded with what the tool is before the branching behavior. Nothing is redundant and no sentence could be dropped without losing 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 single optional-parameter read tool with full annotation coverage and no output schema, the description covers both branches and the content of each result set. The remaining gap is modest: it does not name the folder identifier source or note anything about result size, but an agent can call this correctly from what is given.

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 0%, so the description carries the full burden, and it does: it explains precisely what folderId changes about the result set in both presence and absence cases. What it does not clarify is where a folderId value comes from (i.e., that it is drawn from the folder listing produced by the no-argument call), which would have made it a 5.

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 states the resource (the reader's wishlist) and spells out the two distinct result modes: folders when no folderId is supplied, books within a folder when it is. It is clear enough to distinguish from list_library and list_shelves by the word 'wishlist', though it does not explicitly contrast itself with those 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?

It implicitly tells the agent how to use the single parameter (omit it to enumerate folders, supply it to enumerate books), which is genuine usage guidance. However, there is no explicit statement of when to reach for this tool versus list_library, list_shelves, or the add_to_wishlist counterpart, so the agent must infer placement in the workflow.

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