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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the description earns credit for adding error semantics instead: a 404 when the user is missing and an empty list when they have no bottles. It does not discuss the visibility/privacy model of 'public shelf' beyond the name, so not a full 5.

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?

Three short sentences, front-loaded with what the tool returns and scoped by whose data it returns, then requirements, then edge-case behavior. No filler or redundancy.

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 list tool with full annotation coverage and a fully described 7-parameter schema, the description supplies exactly what structured data cannot: the identity requirement, the sibling-equivalence for filtering/paging, and the 404/empty-list outcomes. Nothing needed to call it 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 description coverage is 100%, so the baseline is 3, but the description adds real value by stating that username or userId is required even though the schema marks zero required parameters. It also maps status/query/paging behavior onto the sibling tool rather than re-describing it, which helps without duplicating 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 and resource ('List bottles') and immediately scopes it to 'another user's public shelf', which cleanly separates it from list_my_bottles and get_user_bottle. An agent can identify the tool 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?

The description says the target is another user and that 'username or userId' is required, plus it cross-references list_my_bottles for status/query/paging semantics. It gives clear context but no explicit exclusion (e.g., 'for your own shelf use list_my_bottles'), so it falls just short of a 5.

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