capcut_add_keyframes

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

With no annotations, the description carries the full burden and does disclose the key behavioral trait: 'Replaces that property's keyframes' (a destructive, overwriting write) and 'Dry-run by default'. Unit conventions for every property are also given. It does not state permission needs, undo/reversibility, or the shape of the dry-run plan, so it adds substantial but not complete behavioral context.

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 core action is front-loaded and every clause carries information (units, easing names, replacement semantics, dry-run default); there is no filler. It is dense and a single long run-on sentence, but nothing is wasted.

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 7-parameter, 5-required mutation tool with no annotations and no output schema, the description covers replacement semantics, dry-run behavior, unit conventions and easing taxonomy. The main remaining gap is the absence of any description of what the dry-run plan returns, which matters given there is no output schema.

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 only 43%, so the description must compensate, and it does: it defines the meaning and units of every value in the property enum (1 = half the canvas, scale 1 = 100%, degrees, alpha 0-1, -1..1 for brightness/contrast/saturation) and maps each ease value to CapCut's Aceleracion/Desaceleracion terms. Draft, track and the points/value payload are left to the schema.

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 and resource ('Animate one property of the segment at start_s'), which clearly separates it from sibling tools like capcut_add_animation or capcut_set_clip. The scope ('one property') is explicit. It stops short of naming an alternative sibling outright, so it is clear but not fully sibling-differentiated.

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?

Usage is implied by the scope statement and the dry-run default, but there is no explicit when-to-use/when-not, no mention of prerequisites beyond the write-time constraint, and no routing to alternatives such as the speed-curve or animation tools. An agent can infer the intent but gets no decision guidance.

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