List books on a shelf

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

The description adds value beyond the readOnlyHint annotation by revealing that the returned data includes per-format download URLs and a cover URL, and that the books are in the shelf's own order. It also notes that the cover image itself should be fetched via get_cover, preventing the agent from expecting the tool to return the image directly. No contradictions with 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?

The description is extremely concise: two sentences that are front-loaded with the primary action and contain only essential information. Every sentence earns its place by clarifying purpose, prerequisites, or output 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?

Given the absence of an output schema, the description explains the key elements of the returned data (download URLs, cover URL) and the ordering. It is sufficient for a simple list tool with two parameters. A minor improvement would be to hint at additional fields like titles or authors, but the current level is still adequate.

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% (both parameters have clear descriptions). The description reinforces the source of shelf_id ('from list_shelves') but does not add new semantic details for offset beyond what the schema already provides. The description adequately complements the schema without repeating it.

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 states the action ('lists the books on a shelf'), specifies the ordering ('in the shelf’s own order'), and provides context on how to obtain the shelf_id ('Shelf ids come from list_shelves'). It also distinguishes the output content from the sibling get_cover tool, making the purpose specific and unambiguous.

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 explicitly tells the agent that shelf_ids must be obtained from list_shelves, establishing a clear prerequisite. It implies appropriate usage for retrieving books on a specific shelf with download URLs, though it does not explicitly exclude use cases best served by siblings like search_books or list_books.

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