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

Annotations already declare the tool read-only and idempotent, and the description adds valuable non-obvious behavior beyond those hints: empty results are meaningful information rather than errors, art is always served at the release level, and linked URLs are not rehosted. The copyright/CC0 note also explains an important legal implication.

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 compact and content-dense. Each sentence carries meaningful information: outputs, empty-set behavior, release-group resolution, and rights/linking semantics. There is no filler or repetition of schema content.

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 read-only lookup tool with rich parameter and output schema coverage, the description covers essential edge cases and nuances: empty art sets, release-group auto-resolution, and non-rehosted image URLs. The agent has enough context to invoke the tool correctly and even to interpret unusual responses.

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%, and both parameters are already described in the schema. The description reinforces the release/release-group MBID distinction and explains release-group resolution, but it does not substantially add syntax or format details beyond what the schema provides, making the schema baseline of 3 appropriate.

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 clearly identifies the tool as retrieving Cover Art Archive images for a release or release-group MBID and specifies the exact kinds of information returned: front/back flags, image types, full-resolution URLs, and thumbnail URLs. It is distinct from sibling entity-specific lookup tools because it targets art rather than core metadata.

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 gives clear usage context: accepts release or release-group MBIDs, automatically resolves release-group MBIDs to a representative release, and returns an empty set instead of an error when no art exists. It does not explicitly compare to sibling tools, but the purpose and behavior are specific enough for an agent to select this tool appropriately.

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