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

Annotations already declare readOnlyHint=false, destructiveHint=true, and idempotentHint=true. The description adds meaningful context beyond them: it spends AI credits, queues asynchronously, and returns a new pending asset rather than mutating the source in place. Minor gap in not tying the credit cost to the consuming project/workspace parameters.

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, front-loaded with what it does, followed by the prerequisite and the cost/return behavior. No filler.

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, yet the description still notes the return shape (a new pending asset) and the follow-up tool to poll it (media_assets_get), plus the credit-spend caveat and estimate prerequisite. Nothing an agent needs to invoke it correctly 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 coverage is 100%, so all five parameters—including targetResolution's enum and idempotencyKey's retry semantics—are already documented. The description echoes the 1080p/4k values but adds no syntax or format detail beyond the schema. 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 (upscale) and resource (one stored video asset) with explicit scope (1080p or 4k) and vendor (ByteDance). An agent can distinguish this from unrelated siblings like media_assets_get or generation_video_create without opening any 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?

Explicitly names the required prerequisite ('Call media_upscale_estimate first'), which routes the agent to the correct preceding step. It doesn't state when-not to use it or frame it against alternative upscaling paths, but the context is clear.

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