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

Annotations already declare read-only, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavior: the credit must be cited, and challenges return questions only ('answers are earned by looking'), which sets expectations about incomplete content. The prompt-injection caveat about stranger-written notes lives in the schema rather than the description, so it is not double-counted here.

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 core action is front-loaded in the first clause and the returned contents are packed into a single colon-delimited list, with the id-source instruction last. The parenthetical asides ('cite it', 'questions only, answers are earned by looking') are load-bearing rather than filler, though the sentence is long enough that the list becomes dense.

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 no output schema, the description carries the burden of describing the return payload and does so field by field, including the citation obligation. For a read tool whose annotations already cover safety and idempotency, this is close to complete; only pagination or size expectations are unaddressed.

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 four parameters are already documented in detail, including the optional visitor notes and the name-required-for-writing rule. The description only adds the hint that piece_id comes from a room's route, which is marginal over the schema. Baseline 3 is appropriate.

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 one piece in full') and then enumerates exactly what comes back: title, author, date, license, credit, bilingual description, context, how to look, curious fact, guide voices and challenges. This is unmistakably different from get_room, search_pieces or recommend_piece without opening any schema.

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 closing sentence 'Use an id from a room's route' gives a concrete acquisition path and implies the get_room → route → get_piece workflow. It does not name an alternative (search_pieces, piece_of_the_day) or state when-not to use it, so it falls short of a full routing rule.

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