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

Annotations only say readOnlyHint=false, openWorldHint=true, destructiveHint=false. The description goes far beyond: public visibility, exactly 24-hour lifetime, retry-once behavior, the credit cost model (100 credits per correct answer, paid for 24h, capped by max_answers), a 100-credit balance prerequisite, and a compliance warning that paid watch time may count as artificial engagement. This is exactly the behavioral context annotations cannot carry.

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 value proposition and mechanics, then cost, then the pre-call checklist, then the sibling routing note. Dense but every clause is functional; the only mild cost is length in a single paragraph.

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 mutation tool with no output schema, the description covers cost, duration, visibility, prerequisites, retry semantics, failure/bypass guidance (suggest_quiz_questions), and a user disclosure note. Nothing needed to invoke it correctly 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 coverage is already 100%, so baseline is 3. The description adds real value on top: it explains the max_answers spend arithmetic, that duration_sec can be omitted for TikTok/YouTube but is required elsewhere, and that questions must come from the user since the agent cannot watch the video.

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+resource ('Create a watch quiz') plus the exact mechanics: viewers watch full length, answer one counting question, right answer earns points, wrong first answer gets a retry. It also distinguishes itself from the sibling boost_post's embedded watch_quiz, so an agent can route correctly.

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?

Explicit pre-call checklist: 'get the questions AND answers from the user (or run suggest_quiz_questions and have them confirm), and confirm max_answers and the maximum spend.' It also names the alternative ('To add a quiz to a boost of the same video, use boost_post's watch_quiz instead'), so both when-to-use and when-not are covered.

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