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

Annotations already declare readOnly=false, idempotent=true, destructive=false, so the agent knows this is a safe-to-repeat write operation. The description adds the partial-update behavior ('any subset') which is not in annotations, but doesn't disclose anything about return values or external side effects (openWorldHint).

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 a single sentence, front-loaded with the action ('Update a quiz') and immediately explains the key semantics of the updates parameter. No wasted words.

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?

Given the large nested schema and comprehensive annotations, the description is sufficient for an agent to understand the tool's role. It lacks details about return values, but no output schema is expected, and the schema's thorough field descriptions compensate. A brief note about applying themeCustomization automatically would be helpful but not essential.

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?

The schema provides 100% coverage with detailed descriptions for every field, so the baseline is 3. The description adds a high-level summary of updateable settings and the 'any subset' behavior, but this information is also present in the schema's updates field description ('Partial quiz settings object; only included fields are updated').

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 states 'Update a quiz' with a clear verb and resource, and lists the categories of settings ('title, description, format, template, timing, music, TTS, publish status, etc.'). This clearly distinguishes it from sibling create/delete/list tools.

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 clearly implies partial updates ('accepts any subset of quiz settings'), giving context on when to use this tool for modifying existing quizzes. It does not explicitly name alternatives like quiz_video_create_quiz or quiz_video_delete_quiz, but the update context is unambiguous given the tool name and siblings.

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