ygo_card_printing_prices

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

With no annotations, the description carries the full burden and does well: it discloses the null-price convention, why nulls occur (no public per-printing feed for KR/DE/FR/IT/SP/PT/SC/TC), and the returned column set. It omits latency and the fact that cost scales with maxSets is only visible in the schema, so it stops short of fully characterizing the call.

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?

Front-loaded with the highest-signal sentence ('USE THIS for any question about...'), then coverage, then the null semantics. The closing 'Never infer a price from rarity' and 'Do not answer from memory; call this tool first' are near-duplicates of the same warning, costing one sentence of redundancy.

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?

There is no output schema, yet the description fully describes the return shape (per-printing rows with set code, set name, rarity, language, nullable price) and the regional coverage limits. For a read-only pricing tool with only three simple parameters, nothing an agent needs to call it correctly or interpret the result is missing.

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%, so all three parameters (cardName, maxSets, includeLive) are already documented, including the '2 upstream requests per set' cost note. The description adds no parameter-level meaning beyond that and does not mention that cardName must be English or what includeLive=false changes in the response.

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 and scope: a per-printing price table keyed by set code, set name, rarity and language, with explicit example questions ("which printing is cheaper", "how much is the Secret Rare"). It clearly stakes out a niche distinct from generic price lookups, but it never names the obviously overlapping siblings (ygo_check_prices, ygo_market_query, ygo_card_dossier), so an agent must infer the boundary from the phrasing alone.

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 exactly which user questions route here, enumerates coverage per region (EN via TCGplayer, JP via Yuyu-tei, AE via TCGCorner) and which regions return null, and closes with an explicit anti-pattern: never infer a price from rarity, call this instead. Both a positive trigger and a negative condition are spelled out.

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