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

With no annotations, the description carries the full burden and does disclose key behavior: it 'preserves the shot still as the source frame, replaces the prior primary video reference, and keeps the result inside the edit.' This tells the agent about source frame handling, that a prior primary video reference is replaced (mutation side effect), and the scoping. It does not mention rate limits, error conditions, or whether other shot media refs are affected.

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 sentences, front-loaded with the core action and scope, followed by behavioral effects. No filler words and every sentence earns its place.

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 a generation tool with 9 params, full schema coverage, and no output schema, the description covers purpose, usage context, and key side effects. It is slightly short on explicit alternatives to route against siblings like generate_video and generate_video_audio, but overall completeness is strong.

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%, so the schema already documents all 9 parameters with semantics (model, prompt, duration, volume, etc.). The description adds no parameter-specific detail beyond what the schema provides, so baseline 3 is appropriate.

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 states a specific verb+resource ('Generate a video for one existing edit shot') and immediately distinguishes scope ('attach the queued media to that shot immediately'), separating it from standalone video tools like generate_video. The phrase 'inside the edit instead of presenting it as standalone media' explicitly differentiates from siblings.

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?

The description gives clear context: 'Use this for project and timeline builds,' which guides when to use it versus standalone generation. However, it never names specific alternatives (generate_video, run_video_workflow) or states exclusions, so it lacks the explicit when-not guidance needed for a 5.

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