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

Annotations declare non-read-only, non-destructive, non-idempotent, so the safety profile is already covered. The description adds real value beyond that: the operation is asynchronous (an 'export job' that 'completes' later) and the output surfaces through get_status rather than the immediate response, plus it is 'free', a cost signal 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?

Two short clauses, front-loaded with the action and its source timeline; nothing is padded. The 'free' note and the async follow-up pointer both earn their place, though the sentence could be tightened slightly.

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, and the description correctly fills that gap by telling the agent the export_url arrives via get_status rather than in this call's response. For a single-parameter, non-destructive tool this is nearly complete; only the relationship to the 'render' sibling is unaddressed.

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% with a single required 'project_id', so the schema carries the parameter documentation. The description adds no format, constraint, or sourcing detail for project_id, 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 ('Render the finished video from the editor timeline'), which is clear on its own. However, the sibling list contains a tool literally named 'render', and the description never distinguishes export_video from it, leaving ambiguity about which one produces the final deliverable.

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?

Usage is implied rather than stated: call this when you want the finished video. It does name get_status as the follow-up step, which is helpful workflow context, but there are no explicit when-not conditions and no explanation of how it relates to the 'render' sibling.

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