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

With no annotations provided, the description carries the full burden, and it delivers richly: it discloses the pinning behavior (duration_authored=true), the override of derived duration, the fixed-canvas effect, clipping semantics, clamping to 1..600 seconds, and the release path. This is far beyond what the schema or annotations alone would convey.

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 substantial but every sentence earns its place: it states the core action up front, explains the default behavior being overridden, describes edge-case consequences, gives concrete use cases, and names the sibling that undoes the action. No filler or redundant phrasing.

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 state-changing tool with no annotations and no output schema, this description is complete: it defines the operation, the behavioral change, the clamping constraints, the effect on playback/export, and how to reverse it. An agent has everything needed to select and invoke the tool 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 description coverage is 100% and both parameters are already well documented in the input schema, including clamping and frame-rate calculation. The description adds context about the effect of the seconds value but does not need to repeat parameter details; a baseline of 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 and resource: author an explicit composition length in seconds. It clearly differentiates from the default auto-fit behavior and names the sibling fit_duration_to_content, so an agent can distinguish it without ambiguity.

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 explicitly says when to use it—to shorten a comp to a target length or reserve a longer stage—and tells the agent to call fit_duration_to_content to release the pin. It also explains the consequence of content past the end being kept but not played/exported, giving clear decision context.

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