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

Adds genuinely useful behavior beyond the annotations: a 1-credit cost, random draw on every call, and the scarcity risk of narrow filters. However, 'Statements are drawn at random each call' sits awkwardly against idempotentHint=true, since repeating the same call will not return the same statements; the description and annotation pull in different directions. It also never says whether the answer is returned as a separate field or embedded, which matters for a quiz consumer.

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-loads what the tool returns and from where, then adds purpose, then the randomness/scarcity caveat, then cost. Every sentence carries information; the only mild padding is the CC BY-SA attribution, though that is defensible since license terms may need to be surfaced to users.

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?

For a zero-required-parameter read tool with a fully documented schema and no output schema, the description covers source, license, filtering axes, randomness, pool-size risk and cost. The one gap is the shape of a returned statement (fields present, whether the answer is separated), which an agent cannot infer from the schema alone.

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 already documents amount (1-50, default 10), category (id 9-32 or name) and difficulty (easy|medium|hard, default mix), so the baseline is 3. The description adds only marginal semantic value by noting the default is 'mixed' and that narrow category+difficulty intersections shrink the pool, which is a useful interaction hint but not parameter-level detail beyond the schema.

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 resource and format ('True-or-false quiz statements with the correct answer') plus the source (Open Trivia Database) and the selection axes (category, difficulty, or mixed). The line 'the true/false bank is smaller than the multiple-choice one' implicitly but clearly separates it from the sibling trivia_questions tool, so an agent can pick the right one without opening a 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?

Gives concrete use contexts ('quick rounds, icebreakers and classroom warm-ups') and a real usage caveat: narrow category plus difficulty combinations may return only a handful because the true/false bank is small. It stops short of naming an alternative tool (e.g. trivia_questions for multiple choice, trivia_question_count to check availability) or saying when not to use it, so it is clear but not exhaustive.

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