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

With no annotations, the description carries the full behavioral burden and does so thoroughly. It discloses idempotency for repeated identical start values, bounded stopping at frame 0, welded caption lines being left behind, morpha bands moving as one unit, and failure modes for empty/always-present groups. An agent can predict side effects and preconditions without additional documentation.

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?

The description is longer than average but every sentence contributes a distinct behavioral or routing fact. It is front-loaded with the core action and analogy, then layers container semantics, constraints, exceptions, and alternatives in a logical order. Given the tool's complexity, the length is justified and not bloated.

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 mutation tool with no output schema and no annotations, the description is remarkably complete: it explains the core behavior, edge cases, failure conditions, interaction with nested elements, and alternatives. The only thing missing is return-value details, but that is not necessary for correct invocation. An agent has enough context to decide when and how to call this tool.

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% and the schema already documents each parameter well, so the baseline is 3. The description adds value beyond the schema by clarifying that 'start' is interpreted as the group window's absolute destination and that calling it twice with the same value is a no-op. It also reinforces the accepted elementId forms and projectId selection behavior, though these largely mirror the schema.

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 opens with a specific verb and resource: 'MOVE a group and everything inside it along the timeline, keeping its internal timing intact.' It clearly distinguishes this operation from siblings by naming set_group_window and set_layer_block as the clipping/single-layer alternatives. The intuitive 'slide this whole section later' phrasing anchors the tool's purpose immediately.

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 explicit conditions for use: move a whole group subtree as a rigid body, while clipping should use set_group_window and single-layer moves should use set_layer_block. It also states when the operation fails (empty group or always-present layer), which helps the agent avoid invalid calls. This is strong when-to-use and when-not-to-use guidance.

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