illustrator_set_reference

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

Annotations already declare destructive/idempotent, but the description goes well beyond them: it specifies the layer is locked, dimmed, and non-printable, that repeat calls replace the prior reference, that removal mode deletes the layer outright, that the active artboard drives fit/center, and that dominant color extraction is conditional on Pillow. That is the kind of side-effect detail annotations cannot carry.

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?

Front-loaded one-line purpose followed by clearly labeled CONTRACT/WHEN TO USE/KEY CONCEPTS/EXAMPLES/NOTES sections, each carrying non-redundant content. It is longer than strictly necessary, but no section is filler.

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 single-parameter mutation with a declared output schema, the description covers the destructive clear path, idempotency, persistence semantics, and environment dependencies. Nothing an agent needs to invoke or avoid this tool correctly is missing.

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 text describes each field, but the description adds meaning beyond it: file_path omission is the clear signal ('omit file_path'), opacity is motivated ('dim tracing' via the 50 example), and fits are tied to the active artboard. The one gap is the boolean 'fit' flag, whose semantics come only from 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?

States a specific verb+resource ('set or clear a reference image on a locked background layer') and immediately distinguishes itself from the closest sibling (illustrator_place_file) by naming the dedicated '__reference__' layer and tracing use case. An agent can tell what this does without opening the schema.

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?

A dedicated WHEN TO USE block gives both the set case (preparing a reference overlay before tracing) and the clear case (omit file_path). It does not name alternative tools for when a reference overlay is the wrong choice, so it falls short of a full 5, but the when/when-not conditions are explicit.

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