get_readlist_book_previous

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

The description adds no behavioral context beyond the readOnlyHint annotation. It does not explain what 'previous' means in terms of ordering, what happens if no previous book exists, or any other edge cases. The annotation itself covers safety, but the description is essentially a restatement of the tool's name, providing no additional transparency.

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 a single, front-loaded sentence that efficiently communicates the core functionality. There is no wasted words or redundant 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 simple read-only getter with an output schema and readOnlyHint annotation, the description provides sufficient information. The main gap is not clarifying navigation order or when to prefer this over get_book_previous, but these are more relevant to usage guidelines. Overall, the description is complete enough for selection and invocation.

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. While it does not explicitly define readlist_id and book_id, the phrase 'previous book in a readlist' implies book_id is the reference book and readlist_id identifies the list. The parameter names are self-explanatory, but the description lacks explicit mapping or details about required format or behavior.

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 a specific verb ('Get') and resource ('previous book in a readlist'), which precisely distinguishes it from siblings like get_readlist_book_next and get_book_previous. The phrase 'in a readlist' narrows the context and avoids ambiguity.

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 usage is implied: it is used when you need the previous book within a readlist. However, it does not explicitly contrast with similar tools like get_book_previous (which may operate in a series context) or get_readlist_books, nor does it mention any exclusions or prerequisites. This is an implied-use case, not clearly differentiated guidance.

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