assemble_highlights

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

With no annotations, the description carries the burden, and it usefully discloses the auto-normalization of resolution/fps/audio rate plus that clips need not match — meaningful behavior not visible in the schema. It does not mention that a new file is written to disk, how existing outputs interact with `overwrite`, or any failure modes for mismatched/unreadable clips.

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?

Two tight sentences with the core operation first and the normalization caveat second; nothing is redundant or padded.

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 an eight-parameter, no-annotation, no-output-schema tool, the description plus fully documented schema covers what an agent needs to invoke it. The gap is selection guidance against `concat`/`xfade_transition` and the on-disk side effect, both minor given the schema's `output` and `overwrite` docs.

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 all eight parameters (fps, width, height, output, duration, overwrite, transition, clips) are already documented inline. The description only restates normalization and transition semantics already present in the schema, adding no syntax, format, or constraint detail beyond it.

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 concrete verb and resource ("stitch two or more clips into a single video") plus the available transition modes, so an agent can tell what it produces. However, it never distinguishes itself from the closely overlapping siblings `concat` and `xfade_transition`, which is the main ambiguity for selection.

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 requirement of two or more clips and the cut-vs-xfade choice imply when the tool applies, but there is no explicit statement about when to prefer it over `concat` or `xfade_transition`, nor any preconditions. Usage must be inferred from the tool name and sibling list.

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