List libraries

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

With no annotations, the description must convey behavioral traits. It clearly implies a read-only listing operation and lists the output fields, but it does not disclose potential performance implications, pagination behavior, or prerequisites. For a simple list tool this is adequate but not rich.

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 sentence that directly states what the tool does and what output to expect. No filler or irrelevant details, making it appropriately concise and front-loaded.

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 tool's low complexity (no parameters, simple list output), the description sufficiently covers the return values by naming the included fields. It lacks an explicit note about output shape or ordering, but these are not critical for a basic listing tool.

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, so the schema provides no meaningful constraints. Descriptions of parameters are unnecessary; the baseline for 0 parameters is 4. The description does not need to add parameter semantics.

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 tool lists libraries in the BookOrbit instance and specifies the exact data returned (book count, total size, per-format counts). This is a specific verb+resource and differentiates it from sibling tools like list_collections or get_library_stats.

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 implies this tool is for retrieving a list of libraries with aggregate counts, but it does not explicitly state when to use it versus alternatives like get_library_stats or get_library_statistic. There is no exclusion or mention of trade-offs.

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