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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, and openWorldHint=true, so the safety profile is covered. The description adds nothing beyond the purpose: it does not say whether the source is preserved, whether the result is a new job (requiring get_job polling), or that the same request repeated costs credits again.

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?

It is a single front-loaded sentence with zero filler, which is good structure. It is arguably too terse rather than verbose – the marginal words needed for when-to-use and output behavior are absent.

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?

There is no output schema, so the description should say what comes back (a job id the agent must poll with get_job) and whether a credit cost applies. Neither is mentioned, leaving an agent unable to chain the call correctly from the definition alone.

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%, documenting start_seconds, end_seconds, source_id chaining, and the video_url vs upload link rule. The description adds no parameter meaning beyond the schema, so the baseline of 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 effect ("keeps only the part of a video between two times"), which reads as a trim operation and is distinguishable from compress/convert/rotate siblings. It falls short of a 5 because it never names an alternative or states the boundary case (e.g., that it produces a new video rather than editing in place).

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?

There is no guidance on when to pick this over make_highlight_video, create_ai_clips, or export_clips, and no prerequisites are stated. The agent must infer the use case entirely from the one-line purpose.

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