Set Clip Duration

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

Adds substantial behavior beyond the annotations: atomic pre-checking across all clips, refusal to overlap the next clip, keyframe-stranding rejection unless keyframe_policy=preserve, read-back verification, and restoration of the original end if Premiere clamps or ignores the write. It also discloses the linked-partner default and the same-end-offset rule that preserves J/L cuts. This is far richer than the readOnly/destructive/idempotent hints.

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?

One dense paragraph, but front-loaded with the core action before the constraints and edge cases. Each clause carries real information (atomicity, clamp fallback, keyframe policy, linked offset). It is slightly overloaded and would read better split into behavior vs. constraints, 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?

A mutation tool with five parameters and an output schema; the description covers the failure modes, safety guarantees, and default behaviors an agent needs before invoking. Return values need not be explained since an output schema exists. Nothing material 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 description coverage is 100%, so the baseline is 3. The description nonetheless reinforces the mutual-exclusivity of duration_seconds/end_seconds and, more importantly, adds cross-parameter semantics absent from the schema: include_linked partners receive the change applied as the same end offset, preserving J/L cuts. That interaction knowledge justifies a step above baseline.

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?

Names a specific verb (set), resource (one timeline clip's visible duration), and implementation detail (moves only TrackItem.end while keeping start fixed). This immediately distinguishes it from siblings like set_clip_start_time, trim_clip, and move_clip. It also closes with a redirect for the adjacent use case (speed changes).

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?

Explicitly routes the agent to alternatives: 'Use this instead of speed changes, which Premiere does not expose to scripting.' It also states the exclusivity rule for duration_seconds vs end_seconds and the still-image extension use case. It does not, however, contrast with the other trimming siblings (trim_clip, set_clip_start_time), so routing is partially covered.

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