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

Annotations only say it is non-read-only and non-destructive; the description adds the operationally critical facts: no credit cost, minutes-long runtime, that progress and the download link come via get_status(wait_sec), and that share creates a PUBLIC page. It also discloses the failure modes (run still producing, shots without clips).

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?

Front-loads what is produced, then cost, then duration/progress mechanism, then flag-specific caveats, then refusal conditions. Dense but every clause carries information an agent would otherwise have to discover by trial.

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?

With no output schema, the description still tells the agent how results surface (get_status polling then a download link) and covers cost, latency, safety of the public share, and refusal conditions. Nothing needed 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 67%, with share and allow_missing already documented inline. The description reinforces both with the consequence of each ('PUBLIC to anyone with the link', 'shorter film'), which adds decision-relevant meaning beyond the schema. project_id remains undescribed in either place.

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 ('Assemble the finished cut and export the film file') and pins down the scope by defining exactly what the exported cut contains: score, narration, seams, fades and prior human edits. That resolves ambiguity against siblings like apply_plan, build_plan and run_control without needing their schemas.

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?

Gives explicit conditional guidance for both optional flags ('only when the person asks' for share, 'only when the person accepts a shorter film' for allow_missing) and names the two preconditions under which the call is refused. An agent knows both when to call and when not to.

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