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

Annotations already declare this as a safe, idempotent, read-only lookup, so the description doesn't need to cover safety. What it does add is the payload: the clip's video link plus an ffmpeg recipe for compositing over an image or video, which tells the agent what practical follow-up the result enables.

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 front-loaded sentence with no filler; the resource, the lookup key, and the return content all appear in a single clause chain.

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?

With no output schema it is appropriate that the description sketches the response (video link, ffmpeg recipe). For a one-parameter read tool with full annotation coverage, that is close to complete, missing only guidance on failure or missing-id behavior.

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?

There is a single parameter at 100% schema coverage, and the schema already says it is 'The id from search results'. The description adds nothing about the id format or source beyond that, so 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?

The description names a specific verb and resource ('One green screen clip by id') and its scope of return ('video link and an ffmpeg recipe'). It implicitly contrasts with the list/search siblings by saying 'one ... by id', though it never names search_green_screens explicitly.

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?

Usage is only implied: the schema note 'The id from search results' hints this follows a search, but the description itself gives no when-to-use or when-not-to-use guidance versus search_green_screens or get_collection.

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