fablecut_track

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

With no annotations, the description carries the full burden and does well: it discloses the execution environment (open tab vs headless Chrome/Edge), that results are persisted to props.tracks, that an existing name is extended/replaced over the tracked range, and that match quality (>=0.8) and lost-region locations are reported. It stops short of stating permission or locked-clip semantics beyond the force flag.

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?

It is front-loaded with the core action and the optional apply step, and given a 14-parameter tool most clauses earn their place. The prose is a dense single paragraph with stacked parentheticals, which makes it heavier to parse than ideal, but there is little outright padding.

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 complex, no-output-schema tool the description covers the essentials an agent needs: what is produced (a named track), the two application modes in the same call, target-selection heuristics, execution venue, and how to verify the result. Nothing required to invoke it correctly is missing.

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 100%, so the baseline is 3, but the description adds real meaning beyond the schema by explaining the interplay between region, point (+size), and apply (region-less implies following the mask) and by describing how the name default is derived. That relational context is not recoverable from the field descriptions alone.

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 first sentence states a specific verb (follow/motion track) and resource (something in a video clip, frame by frame), and it names its own output artifact (a named track stored on the clip). It also routes the agent to fablecut_scopes for verification, so it is distinguishable from siblings despite there being no direct tracker alternative.

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?

It states when and how to use it: pick a detailed target (corner, logo, text, eye) rather than a flat area, and use apply:{mask} with no region to inherit the mask's coverage. It does not name a competing tool to prefer or give explicit exclusions, but the practical selection guidance is clear.

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