setLayerExpression

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

With no annotations, the description carries the entire behavioral burden. It does convey the three mutation modes including removal, but says nothing about permission requirements, whether an existing expression is silently overwritten, error behavior on invalid expressions, or the effect on already-keyframed values.

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?

A single front-loaded sentence that enumerates the exact action set with zero filler. It is appropriately sized, though the same brevity is what leaves usage and behavioral gaps.

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 no-annotation, no-output-schema mutation tool with six parameters, the description is only minimally sufficient. It names the operation but omits layer-targeting guidance (compName vs layerName vs layerIndex) and any failure or overwrite semantics an agent would need before calling 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 100%, so all six parameters (including the name/index layer-selection pair and the null-to-remove expression semantics) are already documented in the schema. The description adds no syntax or selection-priority detail beyond that, 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 set (add, modify, remove) against a specific resource (an expression on a layer property), which is unambiguous on its own. It does not, however, differentiate itself from near-neighbors like setLayerProperties or setLayerKeyframe, so an agent must infer the boundary from the name alone.

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?

There is no guidance on when to reach for this tool versus setLayerProperties (static values) or setLayerKeyframe (keyframed values). No prerequisites, no mention of what happens if the expression is invalid or the referenced property does not exist.

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