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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds useful scope context ('accepted friends') but does not disclose behavioral details like pagination, sorting, or return format. This adds some value beyond annotations but is not extensive.

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 of five words, front-loaded with the action and resource. Every word earns its place, with no redundant or vague filler.

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 list tool with zero parameters, rich annotations, and an output schema, the description is complete. It states the purpose and scope clearly, and return values are presumably defined in the output schema.

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 baseline is 4 per the rubric. The description correctly focuses on the action and scope; there is no parameter information needed.

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 'List the current user's accepted friends' uses a specific verb and resource, with the qualifier 'accepted' clearly distinguishing it from sibling tools like list_received_friend_requests and list_sent_friend_requests. It is immediately clear what the tool does and how it differs from friends-related alternatives.

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 clear context by specifying 'current user's accepted friends', which implicitly excludes pending or sent requests. However, it does not explicitly name alternative tools or state when-not-to-use, so it falls short of a 5 but provides solid contextual guidance.

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