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

Annotations already declare destructive, idempotent and closed-world behavior, so the bar is lower. The description adds real value by disclosing atomicity ('one sequence transaction') and the 100-item ceiling, which the annotations do not cover. It omits, however, what happens on conflict or partial failure.

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?

A single front-loaded sentence with zero waste; the resource, the scope, and the batch limit all land immediately.

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?

Output schema and annotations cover returns and safety, so the description need not restate them. It adequately conveys scope and atomicity, with only expectedRevision conflict semantics left 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 the baseline is 3. The description loosely maps 'timing, trim, layer, or state' onto the update fields, but adds no syntax or constraint detail beyond what the schema already documents.

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 (Update) plus the resource (timeline clips/items) and the batch scope ('up to 100 timeline items in one sequence transaction'). This distinguishes it from the single-item update_timeline_clip sibling, though it never names that sibling explicitly.

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 'batch' framing and the 100-item cap imply when to prefer this over the single-item sibling, but there is no explicit when-to-use/when-not statement, no mention of expectedRevision conflict behavior, and no guidance on partial failures.

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