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

Beyond the annotations it discloses visibility ('Both are public to anyone who has the link'), the retention policy ('A short link nobody opens for 90 days goes away, a page after a year'), and regeneration semantics ('The same links always give the same link; to change a set, call make_set again'). These are exactly the behavioral facts an agent cannot infer from readOnlyHint/idempotentHint alone.

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 is front-loaded in the first clause, and the long parenthetical examples of use cases are the only mildly expendable material. Overall dense and well-ordered, though slightly longer than necessary.

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?

An output schema exists so return values need no explanation. With parameters fully documented in the schema and the description covering visibility, expiry, idempotency and use contexts, an agent has everything needed to invoke this tool 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 already 100%, so the baseline is 3. The description adds meaning the schema does not spell out: the title/description pair branches the output mode ('With a title (and a description) it publishes the set as a page...; without one it makes a short link'), clarifying the conditional behavior of those two parameters.

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 gives a concrete verb+resource ('Makes a urlhub set from links') and details the artifact produced (short link opening a page of pictures, titles, descriptions, plus QR code in PNG and SVG). It is clearly the creation tool among its siblings, but it never names featured_sets, preview_links or read_set to draw the contrast explicitly.

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 states concrete contexts for use ('sent to someone, opened later on a phone, or printed as one QR code on a poster'), and gives the update path ('to change a set, call make_set again'), which implicitly rules out a separate edit tool. No explicit when-not or named-alternative routing is provided, so it stops short of a 5.

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