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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered; the description adds two things not in structured data — that the value is the user's live editor state and that the call is free. It does not discuss behavior when nothing is open, which the output schema presumably covers.

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 sentences with zero filler: the first defines the return value, the second defines the trigger, and cost is appended last. The purpose is front-loaded ahead of the usage rule, which is the right order for scanning.

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 zero-parameter, read-only tool with full annotation coverage and an output schema, the description supplies everything an agent needs to decide and call: what it reads and when to read it. The only residual gap is what happens in an empty-selection state, which the output schema can reasonably be expected to explain.

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?

The tool takes zero parameters, so there is no parameter semantics for the description to carry; the baseline for a no-arg tool applies. Nothing is misleading about the omission.

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 concretely what is returned: the video, the second, and the layers the user currently has open and selected in Clypmint. That is a specific resource with identifiable scope, though it does not explicitly distinguish itself from the adjacent get_timeline or canvas_live siblings, leaving the agent to infer the difference.

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?

It gives concrete invocation triggers — read it when the user says "this" or names no video — which is exactly the pronoun-resolution case an agent needs. It stops short of naming an alternative tool or stating when not to call it, so it is clear context without exclusions.

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