append_media

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

With no annotations, the description must carry the behavioral burden; it does disclose that audio and video are retained by default and how track selection changes with media_type. However 'retained' is ambiguous, and nothing is said about create_track (default true) implicitly creating a new track, what happens if the referenced track does not exist, or whether appending is reversible.

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?

Front-loaded with the core action, then the positional default, then the sibling redirect, then the media_type values. Sanitized and dense with no filler, though the 'retained by default' sentence is vague enough to cost clarity.

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?

An output schema exists, so return values need no explanation, and the default-append behavior is well covered. Still missing for a 6-parameter mutation tool: the unexplained create_track flag, whether a timeline must already be open, and whether paths and media_ids can be supplied together.

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 0%, so the description has to compensate, and it does for most parameters: media_type's 1/2 values, track_index's interaction with media_type, and record_frame's omission semantics are all explained. create_track is never mentioned and paths vs media_ids exclusivity is only implied by the opening sentence.

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 (append) and resource (video/audio to the timeline) and names both input sources (media pool ids or absolute file paths). It also explicitly contrasts itself with the sibling add_image for stills, so an agent can distinguish it without opening either 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?

Gives concrete when-to conditions: omit track_index and record_frame to append at the end, use media_type=1/2 to restrict to one track type. It names the alternative tool (add_image) and the condition that selects it (still images with controlled duration).

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