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

Annotations only give the safety flags; the description adds billing behavior ('Never charges') and preservation of the source ('The original video is always kept'), both material for an agent deciding whether to invoke. It does not address repeat behavior despite idempotentHint=false, which would have added further value.

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 tight sentences with the operation and its required ids front-loaded, followed by the two most decision-relevant facts (free, non-destructive). No filler sentences.

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 mutation tool with no output schema this covers purpose, inputs, cost, and source safety, which is enough to invoke correctly. Minor gaps remain around how repeats behave and how the resulting job is polled (e.g. soclo_motion_status), but nothing essential 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 sourceAssetId and redoOf are already documented in the schema. The description restates that redoOf is the finished effects video's requestId, adding no format or constraint detail beyond the structured field, which is the baseline-3 case.

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+resource ('Re-do Add effects'), the target ('the same Library video'), and the two inputs that define the operation. It is clearly distinguishable from soclo_motion_effects_make, though it never names that sibling, so it stops short of the top mark.

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?

The 'Re-do' framing plus the precondition that redoOf must be the requestId of a finished effects video tells the agent when this tool applies versus a fresh make. No explicit when-not-use or named alternative is given, so it is clear context without exclusions.

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