Check Saved Albums

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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, so the safety profile is covered. The description adds value beyond these by disclosing the 20-album cap, the acceptance of URIs in addition to IDs, and the return shape (MembershipStatus.results mapping each album id to a boolean). No contradiction with the read-only annotation.

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 purpose is front-loaded in the first line, and the Args/Returns block is compact and structured. Every sentence earns its place with no filler. It's slightly verbose with the repetition of the cap across the intro and the Args line, but that's minor.

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?

The tool is simple (one required parameter) and has an output schema, so the description needn't explain return values in depth—yet it still names the return type. Annotations cover safety. The description is adequate for a single-param read tool; a small gap is the lack of any note about failure/error behavior when an invalid album ID is passed.

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 0%, so the description must compensate, and it does: 'Album IDs or URIs (up to 20)' adds the critical facts that URIs are accepted (not just bare IDs) and that the array is capped at 20. This goes meaningfully beyond what the bare schema (array of strings) conveys.

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?

'Check which albums are already saved to the library' states a specific verb and resource, and the resource type (albums vs tracks) implicitly differentiates it from the sibling check_saved_tracks. However, it doesn't explicitly name that sibling or any other alternative, so it falls short of the top tier that explicitly distinguishes from siblings.

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 purpose line implies when to use it (when you need to verify album save status), and the 20-album cap conveys a usage constraint. But there is no explicit when-to-use vs alternatives guidance, no exclusions, and no mention of check_saved_tracks or get_saved_albums as related tools an agent might choose instead.

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