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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=false, but the description adds real behavioral context beyond them: it spends no tokens, it produces a fresh timeline (so nothing existing is destroyed), returns an Editor address, and continues in the preview/Export flow. This is useful operational detail, though it does not discuss limits or error behavior.

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 sentences, front-loaded with the core action, then the routing condition, then the id-sourcing and cost note. Every sentence earns its place and there is no redundancy.

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?

Although there is no output schema, the description states what is returned (the Editor address) and where the result plays and renders. It covers the mutation semantics, cost, and sibling alternative, so an agent has everything needed to call it correctly.

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% so the baseline is 3, but the description adds value the schema cannot: it tells the agent where the ids come from ('from list_my_videos') and reinforces ordering as 'play order'. That sourcing pointer meaningfully guides correct invocation.

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+resource ('stitch your videos together in the Switch Editor') and immediately clarifies it puts clips on a fresh Editor timeline rather than rendering a file. It explicitly names and contrasts the sibling stitch_videos, so an agent can route between the two without opening 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 an explicit when-to-use ('the user wants to join, stitch, combine or put clips back to back and keep editing') and an explicit alternative with its differing condition ('stitch_videos is the one that renders a file straight away'). Nothing is left to inference.

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