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

The readOnlyHint annotation already establishes that this is a safe read operation. The description adds useful behavioral context by saying items are grouped by category and include sharing information, but it does not mention pagination, ordering, permission scope, or any other operational caveat.

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 identifies the resource, item types, grouping, and sharing context without wasted words. It is appropriately sized for a zero-parameter list tool.

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 parameters, no output schema, and only readOnlyHint available, the description supplies enough high-level context about what the library contains and how it is organized. It could be slightly more complete by mentioning ordering or response shape, but it is adequate for this simple 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?

There are zero parameters, so the baseline is 4. The description properly avoids inventing parameter semantics and focuses on the resource being returned.

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 identifies the exact resource: the coach's document library containing guides and documents such as links, Google Docs, and files. It also notes grouping and sharing context, which distinguishes it from the create/update/delete library item siblings, though it describes the resource as a noun phrase rather than explicitly stating the list action.

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 tool name and the description of the document library, but the description does not explicitly say when to use this tool, when not to use it, or name any alternative sibling such as create_library_item or update_library_item. For a zero-parameter read tool, the implied browse/list use is reasonably clear but not explicitly guided.

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