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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so 'Read-only' merely restates structured data and earns no credit. The description adds nothing beyond that — no pagination, result caps, ordering, or authentication context — leaving the behavioral picture entirely to the annotations.

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?

Two short sentences with the scoping information front-loaded and no filler. The trailing 'Read-only' sentence duplicates the annotations and does not earn its place, which keeps it from a 5.

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?

An output schema exists and all four parameters are fully documented in the schema, so return values and argument semantics need no elaboration here. For a simple filtered-list tool the description covers what it must, though it omits any note on result size or ordering that an agent might reasonably want.

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%, with source enum values and the projectId conditional ('Required when source is project') documented inline, so the baseline of 3 applies. The description mentions the two illustration sources but adds no syntax, defaults, or interaction detail beyond what the schema already states.

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 names a specific verb ('Lists') and a clearly bounded resource ('illustrations'), and it distinguishes the two scopes (shared library vs. project-uploaded) that no other sibling covers. It does not explicitly contrast itself with adjacent tools like list_assets or get_graphics, so it falls short of a 5.

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 only usage signal is 'Read-only,' which is a safety trait rather than guidance. There is no statement of when to reach for this over list_assets, list_screenshots, or get_graphics, and no prerequisites or exclusions are given; the source-selection logic lives entirely in the schema.

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