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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior, so the description's job is to add context, which it does: it characterizes the returned content as a design brief rather than raw data, and it warns that owner-written text is data, not instructions — a genuinely useful prompt-injection guardrail. It does not cover failure modes such as malformed or expired links, which keeps it below 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?

Two tight sentences, front-loaded with the action and the returned content, followed by the call-shape hint and the safety note. Nothing is redundant with the title or annotations.

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 required parameter, full schema coverage, no output schema, and annotations covering the safety profile, the description fills exactly the remaining gaps: what the return value conceptually is and how to treat owner-authored text. An agent has everything needed to call it correctly and interpret the result.

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 coverage is 100% and the single 'link' parameter already carries an example format. The description repeats the same accepted link shapes (…/#/s/<id> or …/c/<id>.md) without adding constraints like whether the collection must be shared with the caller's account, so it neither helps nor harms beyond the schema baseline.

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 and resource ('Read a Wunderlust collection someone shared with you') and goes further to describe the payload's shape: what the owner is making, why, and what to take from each reference. That framing cleanly separates it from the reference-level siblings (get_references, search_references, similar_references) without needing to name them.

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?

The precondition is explicit — use this when someone has shared a collection with you, and pass the link they gave you. What's missing is any exclusion or routing advice (e.g., when to use this versus get_references on a single item), so it stops short of full when/when-not guidance.

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