list_shelves

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

Annotations already mark the tool as read-only and idempotent, and the description adds valuable behavior beyond that: the data is scraped and best-effort, private profiles raise LoginRequired, and very long shelf lists may be capped. These edge cases are non-obvious and useful.

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 front-loaded: the core purpose is in the first sentence, followed by short, relevant caveats about scope, failure mode, and limitations. Every sentence adds unique information with no 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 simple optional-parameter read-only tool with an output schema, the description covers purpose, default behavior, shelf scope, relation to get_shelf, failure behavior, and a known limitation. Nothing essential is missing for an agent to invoke it correctly.

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?

The only parameter, user_id, has no schema description, so the description carries the burden. It explains the default behavior ('Defaults to the configured user') and implies that supplying user_id targets another profile. It does not spell out the expected user_id format, leaving a minor gap.

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 opens with a specific verb and resource: 'List a user's shelf names.' It further clarifies scope by distinguishing exclusive shelves from custom shelves and ties the output to get_shelf's 'shelf' argument, making the tool's role distinct 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?

It provides clear operational context: defaults to the configured user, covers all shelf types, and explicitly connects the result to get_shelf. It does not explicitly state when not to use this tool or name alternatives, so it stops 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.