Retime a timeline element

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

With no annotations provided, the description carries the full burden. It discloses that the tool is 'Blocked in read-only mode' and works on 'any track'. While it does not detail side effects like conflict handling, it transparently conveys a key constraint.

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 four sentences, each earning its place: purpose, usage guide, alternative, ID source, and behavioral note. No wasted words, well-structured.

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?

Given no output schema and no annotations, the description covers purpose, usage, parameter sourcing, and a key behavioral constraint. It omits error behavior but is otherwise complete for a mutation tool of moderate complexity.

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 50% (only duration and startTime have descriptions in schema). The description adds meaning by mapping 'starts' to startTime and 'how long it lasts' to duration, and specifies that elementId comes from get_project, compensating for undocumented parameters.

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 uses a specific verb 'Change' and resource 'timeline element', clearly stating it adjusts start and/or duration. It distinguishes itself from the sibling tool 'reorder_timeline' by explicitly noting it works on a single element.

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 advises when to use this tool ('nudge a floating audio/overlay element to a new point') and provides an explicit alternative ('To resequence all clips, use reorder_timeline'). It also indicates where to obtain required IDs ('Element ids come from get_project').

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