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

Beyond the annotations (which simply indicate a non-read-only, non-idempotent operation), the description discloses important side effects: it saves a quiz, may derive and save a custom theme when omitted, and when autoRender is true returns a queued render session to poll. It also states that the response always includes a watchUrl. This is useful behavioral context beyond what the structured annotations provide, though it could be more explicit about the default render-queue behavior when autoRender is false.

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 description is four sentences, each conveying distinct, high-value information: the core action, theme recommendation, music default, and response/render details. It is front-loaded with the most important information and contains no filler or 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?

For a tool with 15 parameters, a nested object, and no output schema, the description does a good job explaining the essential response characteristics (watchUrl always present, data.render when autoRender is true). It could also briefly describe the general quiz object shape or mention that a quiz is returned directly even without autoRender, but the combination of high schema coverage and the description's key response notes makes it reasonably complete.

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?

With 100% schema description coverage, the baseline is 3, but the description adds meaningful guidance: it recommends preferring themeDescription/themeCustomization and explains the fallback behavior when they are omitted ('the server derives and saves a topic-based custom theme'). It also clarifies the default vs null behavior for backgroundMusicId. These insights go beyond the parameter schemas and help the agent choose correct inputs.

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 clearly states the tool's specific action: 'AI-generate and save a quiz from a topic.' The verb 'generate' (with AI) distinguishes it from the sibling tool 'quiz_video_create_quiz' (which likely implies manual creation), and it also specifies the input (topic) and output (saved quiz). This is a clear, purpose-specific verb+resource combination.

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 description gives practical guidance on parameter selection: 'Prefer providing themeDescription or themeCustomization' and explains the default music behavior ('Omit backgroundMusicId to use default... set null for silent'). It also explains how to follow up on autoRender ('poll quiz_video_get_render'). However, it does not explicitly mention when to use this tool over sibling tools like quiz_video_create_quiz or quiz_video_create_render, so it falls short of an explicit alternative/exclusion list.

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