Retrieve library statistics

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is fully covered. The description adds that the operation is a GET on /libraries/{id}/statistics and enumerates the statistic categories, but says nothing about auth/permission requirements or response shape.

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 structure is front-loaded and the operation line is useful, but the first line duplicates the title and the second line redundantly repeats 'Retrieve statistics', leaving some wasted text in a very short definition.

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, single-parameter read tool with full annotation coverage and no output schema, the description is nearly complete: it names the resource scope and enumerates the returned statistic categories, which compensates for the absent output schema. Only auth requirements and format details are missing.

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 100% for the single 'id' parameter, so the schema already documents it. The description adds no additional syntax or meaning beyond the schema, making the baseline 3 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 states a specific verb and resource ('Retrieve statistics for a specific external library') and enumerates what the statistics cover (videos, images, storage usage). It distinguishes itself from the generic immich_get_library, though it does not explicitly differentiate from the many other *_statistics siblings in the list.

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?

Usage is implied by the scoping to 'a specific external library', so an agent can infer it needs a library id. However, there is no explicit when-to-use guidance, no mention of prerequisites, and no reference to alternatives such as immich_get_library or immich_get_all_libraries.

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