Add one video to a showcase

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

Annotations already declare non-read-only, idempotent, non-destructive, open-world. The description adds genuine value beyond them by clarifying the side effect ('the video stays where it is in your library and is not moved') and the underlying API constraint. It stops short of stating auth/permission requirements or the response shape.

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?

Three short sentences, front-loaded with the action, then the side-effect clarification, then the rationale for the one-at-a-time design. Every sentence earns its place with no repetition of the schema.

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 two-parameter mutation with no output schema, the description covers what the tool does, its side effect, and its calling pattern. The only gap is the return value / error behavior, which is minor here.

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 both parameters (showcase_id, video_id) are already documented in the schema. The description only reinforces cardinality (one video per call), which the schema cannot convey, but adds no format or ID-namespace detail. 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 and resource ('Add one video to a showcase') and pins the cardinality ('one video', 'once per video'). It also implicitly distinguishes itself from any bulk variant by explaining that the bulk endpoint is deliberately not exposed, so an agent knows exactly what this tool does.

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 a concrete usage rule ('Call this once per video') and explains why no bulk alternative exists, which preempts the agent hunting for one. It does not explicitly route to the sibling remove_video_from_showcase or state prerequisites, so it is strong but not fully explicit about alternatives.

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