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

With no annotations, the description carries the full behavioral burden, and it partially delivers by disclosing that each entry reports a live card count and that `need: true` flags situation decks. It does not state that the operation is read-only, whether counts are cached, or anything about pagination/ordering, so the agent is left guessing on the operational profile.

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?

It is a single compact sentence with the core distinction ('by-situation' vs 'by-domain') and the `need` flag front-loaded. The leading '[KEEP · door]' token is unexplained noise that costs a little clarity but does not bloat the text.

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?

No output schema exists, so the description must explain the return shape — it partly does (live card count, `need` flag), which is adequate for a zero-parameter listing tool. However, it never confirms the core action (listing) or the fields of each deck entry, leaving a small but real gap for a tool whose return surface is entirely undocumented elsewhere.

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?

The tool takes zero parameters, so the baseline is 4. The description correctly adds no parameter detail because there is nothing to parameterize; the mention of `need: true` describes returned data rather than an input.

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 the resource precisely (curated card SETS, split into by-situation and by-domain) and surfaces a distinguishing data attribute (`need: true`). It never states the verb — whether this lists, counts, or opens decks — so an agent must infer 'list/overview' rather than being told.

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?

There is no guidance on when to reach for `decks` versus the obvious siblings `deck_open`, `cards_browse`, or `card_get`. The bracketed '[KEEP · door]' marker is internal jargon that gives the agent no actionable routing condition.

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