get_library_stats

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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds only a scope qualifier ('library-specific') but no additional behavioral context such as return format, aggregations, or behavior when libraryKey is omitted. This falls short of enriching the agent's understanding beyond the 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 a single, tightly worded phrase with no filler or redundancy. It is appropriately concise for a simple tool, though it sacrifices detail for brevity.

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?

With no output schema and a terse description, the tool's return value is not explained. The agent is left guessing what statistics are provided, how they are structured, and how the optional libraryKey affects results. For a tool with only one parameter and no explicit output format, the description should provide more context.

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% with libraryKey described as 'Library section key (optional)', so the schema fully documents the parameter. The description offers no additional semantic value beyond what the schema already provides, earning the baseline score of 3.

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 ('library-specific statistics'), which distinguishes it from sibling tools like get_libraries (which lists libraries) and get_library_items (which lists items). However, it lacks detail on what 'statistics' encompasses, making it clear but not fully specific.

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 provides no guidance on when to use this tool versus alternatives such as get_watch_stats or get_user_stats. There is no mention of prerequisites, context, or exclusions, leaving the agent to infer appropriate usage from the name alone.

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