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

With no annotations, the description carries the full transparency burden and handles it well. It states the exact effect on keyframe values, that relative spacing is preserved, that the whole curve slides, and that keyframe times are not changed. It also explains negative delta behavior ('Negative shifts the curve down/left').

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 core operation is front-loaded, followed by an analogy and concrete examples. Every sentence earns its place: the gesture analogy helps internalize behavior, the times-untouched point prevents a common mistake, and the examples clarify parameter usage.

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 4-parameter tool with no output schema and no annotations, this description is remarkably complete. It covers what changes, what doesn't, how negative deltas behave, and realistic scenarios, leaving little ambiguity for an agent deciding whether and how to call it.

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%, and the description compensates with meaningful context: it defines delta's role, clarifies that elementId identifies a layer, and gives property-specific examples. It doesn't fully document every parameter, but the examples and first sentence add enough semantic value beyond 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: 'Bulk-shift every keyframe's VALUE on one property of one layer by delta.' It clearly distinguishes this from keyframe-time operations by stating 'Keyframe TIMES are untouched,' which separates it from sibling tools that add, remove, or re-time keyframes.

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 use cases: 'move all x by -30px', 'retiming a fade by adjusting its base opacity', 'rotating an existing wobble by 10°'. It does not explicitly name alternative tools or state when not to use it, but the context is clear enough for an agent to select it for bulk value shifts.

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