Plan Reaction Captions

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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuine behavioral detail beyond that: flash-length words merge, overlaps stack, and unknown speakers stay uncolored (no guessed colors). 'Never changes Premiere' largely restates readOnlyHint but usefully reinforces that planning is side-effect free.

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/three tight sentences: the core operation first, then the key merge/stack/coloring rules, then the safety note. Every sentence carries information and nothing is 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 a 10-parameter planning tool with rich annotations and an output schema that covers the return value, the description supplies enough behavioral context (merge, stacking, uncolored unknown speakers) to call it correctly. It stops short of explaining the transcript-revision dependency or ties to the palette-to-word label matching rules, but these are mostly in the 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 100% across all 10 parameters, so the schema already documents frame_rate, gaps, cue limits, and hold behavior with defaults. The description names none of these parameters and adds no syntax or format meaning, so the baseline 3 applies.

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 ('plan') and resource ('stacked, speaker-colored reaction captions') plus the two required inputs, distinguishing it from the write-oriented siblings (build_caption_artifact, create_caption_track) and from planning siblings like plan_speaker_checkerboard. An agent can identify the operation without opening the schema.

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 implies usage by naming the required inputs (a word timeline and speaker palette), which suggests when the tool applies, but it never states when to prefer this over build_caption_artifact or create_caption_track, nor any prerequisite such as needing a transcript revision from get_clip_transcript_uxp. Usage context is inferable but not explicit.

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