ddb_list_library

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the tool's non-destructive nature is covered. The description adds valuable behavioral context by disclosing the login requirement, which is not present in the annotations. No contradiction exists between the description and 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 two concise sentences: the first front-loads the action, the second states the prerequisite. No wasted words or redundant information. It is easy to parse quickly.

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?

This is a simple no-parameter, read-only list tool. The description adequately covers the purpose and prerequisite. While it doesn't describe the return format or pagination behavior, the tool's simplicity and the presence of readOnlyHint make this absence acceptable.

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 tool has zero parameters, and the schema coverage is 100% (empty schema). Per the rubric, a 0-parameter tool receives a baseline score of 4. The description adds no parameter details because none are needed, making it appropriate.

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 uses the specific verb 'List' with a clear resource: 'books and sourcebooks you own in your D&D Beyond library'. It clearly distinguishes itself from sibling tools like ddb_list_characters and ddb_read_book, leaving no ambiguity about its function.

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 states the prerequisite: 'Requires login — run ddb_login first if you haven't already.' This provides clear context for when the tool can be used, though it doesn't mention alternatives. The condition is specific and actionable, earning a score above the minimum.

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