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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so the safety profile is covered. The description usefully adds that the cut starts empty and that the new cut is returned, but says nothing about whether repeated calls create multiple cuts, naming conflicts (maxLength 80 in schema), or where the cut lands in the timeline.

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 tight sentences: the first defines the action and the resulting state, the second states the return value and the next step. Nothing is wasted and the core action is front-loaded.

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 simple two-parameter creation tool with full schema coverage and annotations covering safety, the definition is nearly sufficient: it clarifies the empty-state result and the follow-up tool. Minor gap is the returned cut's shape and whether the new cut becomes the active edit, which the absence of an output schema leaves 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% — both name and threadId are documented in the schema, including the 'from list_threads' provenance. The description adds no further parameter meaning beyond what the schema already supplies, 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 ('Create a new, empty cut') and defines the domain term for the agent ('an alternative edit'), plus anchors it to a thread's timeline. It differentiates itself from add_clips_to_timeline by emphasizing the cut is empty and clips come later, though it never contrasts with duplicate_cut for copying an existing edit.

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?

Provides clear workflow context: call this to start a new edit, then use add_clips_to_timeline to populate it. The threadId schema note points to list_threads for prerequisites. It lacks explicit exclusions (e.g., 'to copy an existing edit use duplicate_cut instead'), which keeps it below a 5.

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