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

Annotations already declare destructiveHint=true, so the destructive nature is covered. The description adds useful behavioral details: the action is voluntary, the owner is blocked and will get an error directing them elsewhere. This goes beyond the structured annotations without contradicting them.

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?

Two sentences plus a return note; every sentence serves a purpose. The primary action is front-loaded, followed by the key exception and return type. No fluff or redundancy.

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 zero-parameter, single-action tool with destructive annotations, the description is complete: it defines the action, the owner limitation, and the return value. No output schema exists, but the return note covers what the agent needs.

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 0 parameters and schema coverage is 100%, so there is no parameter semantics to convey. The description does not need to compensate; baseline 4 is appropriate given the empty schema.

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 action ('Voluntarily leave your current family group') with the resource (family group) and actor ('your'). It clearly distinguishes from sibling tools like remove_family_member (which removes others) and create_family_group (creation). The owner exception also sharpens the scope.

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 when to use it — when you want to leave your own family group. It provides an exclusion: group owners cannot leave and are pointed to deleting the group instead. However, it does not explicitly name alternative tools (e.g., remove_family_member) or give broader when-to-use context, so it falls short of a perfect 5.

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