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

Goes well beyond the annotations (idempotentHint, readOnlyHint=false) by explaining why idempotency matters — an identical render reuses the previous output and spends no credits — and by disclosing a concrete rate limit (~10 renders/hour due to server CPU). It also discloses the async return shape (renderId + status) and the polling requirement, which the annotations cannot convey.

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: purpose first, then cost/limit caveats, then the return-and-poll contract. Every sentence supplies information an agent needs to call and follow up correctly, with 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?

For an async, no-output-schema tool this is complete: it covers what is produced, that it consumes time rather than credits, the throttling ceiling, and how to reach a terminal state. Nothing required to invoke or follow up 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% and both parameters are already documented with their provenance (cutId from get_timeline, threadId from list_threads). The description only refers obliquely to 'clips of a cut', adding no new syntax or constraint information, so the 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 — stitching a cut's clips into one video — which unambiguously separates it from timeline-editing siblings like add_clips_to_timeline or create_cut. An agent can identify the render step 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?

Explains the follow-up flow explicitly ('poll get_render_status until it is COMPLETED or FAILED'), naming the sibling to use next and the terminal conditions. It does not state when to avoid rendering versus alternatives (e.g. estimate_cost first), so it falls short of a full when/when-not pair.

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