set_timeline_duration

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

With no annotations, the description carries the full burden. It usefully discloses the destructive side effect (shortening truncates existing motion) and the timelineId default, but says nothing about reversibility, permissions, or response, leaving meaningful behavioral gaps for a mutation tool.

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?

Three tight sentences, front-loaded with the core action and scope, followed by the parameter default and the safety caveat. No filler or repetition.

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 3-param mutation tool with no annotations and no output schema, the description covers unit, default behavior, and the key destructive consequence. Only the meaning of nodeId and reversibility are left implicit, so it is nearly 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?

Schema coverage is 0%, so the description must compensate. It adds real meaning for two of three params — duration is 'in seconds' and timelineId omitted falls back to the node's first timeline — but nodeId is never explained, leaving one parameter undocumented in both schema and description.

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 (Set) and resource (duration of a timeline), and pins the scope to 'the timeline owned by the node's containing top-level frame,' which tells the agent exactly what is being mutated. It does not explicitly contrast with nearby siblings like set_keyframe_track or apply_animation_style, but the purpose itself is unambiguous.

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 explicit when/when-not guidance: lengthen to make room for animation, do not shorten unless the user asked because it truncates motion. This is strong operational direction, though it names no alternative tool to route to.

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