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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description adds the genuinely non-obvious behavior that results are aggregated per author with four derived counters, one of which ('applied in something delivered') is a cross-resource computation. It says nothing about ordering, limits, or whether counts include unread/archived items, 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?

The purpose and the four metrics are front-loaded, and the usage triggers follow before the parameter note. It is dense but every clause carries information; the only slack is that the metric enumeration could be compressed slightly without loss.

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?

With one optional parameter, full schema coverage, and no output schema, the description is exactly what an agent needs: it discloses what the response contains (per-author counts) so the missing output schema does not blind the agent, and it explains the effect of passing vs. omitting 'name'. Nothing essential for correct invocation is absent.

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% and the 'name' parameter is fully documented there as 'un autor, para ver sus notas una a una'. The description's 'Con name, las notas de uno' mostly restates that, adding only a mild contrast with the aggregate default; no format, matching, or partial-match semantics are given.

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 resource (the authors behind everything the user has saved, i.e. their mentors) and spells out the exact metrics returned per author: note count, read count, reopened-or-not, and applied-in-delivery count. That is far more than a restatement of the name 'list_mentors' and lets an agent distinguish it from a plain book or note listing.

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 three concrete trigger questions (who am I learning from, what have I applied from an author, what have I saved but not used), which maps cleanly onto user intents. It does not name a sibling alternative for the related-but-different case of listing notes or books directly, so it stops short of explicit when-not guidance.

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