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

Annotations already declare destructiveHint=true, openWorldHint=true, and non-idempotent behavior; the description adds genuinely new context by disclosing that the feature is account-gated and must be verified via 'list' before use. It stops short of stating that delete is permanent or what auth is required, which keeps it from a 5.

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?

Front-loaded purpose followed by a scannable action table and concrete examples. Dense but each block earns its place; the examples are slightly redundant with the action list but aid invocation.

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 7-action multi-mode tool, it covers feature availability, per-action parameter requirements, and worked examples, and an output schema exists so return shapes need not be described. Nothing an agent needs to invoke it correctly is 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 coverage is 100%, so the baseline is 3, but the description goes beyond the schema by mapping which parameters each action requires (id/name resolution, conversation_id for add/remove). That action-to-parameter mapping is real added meaning.

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?

States a specific verb+resource ('Manage personal chat lists'), and explicitly distinguishes them from Business labels, which routes the agent away from the sibling manage_labels tool. An agent knows exactly what domain this covers.

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 action list gives per-action requirements (which params each action needs), and it explicitly warns to call action 'list' first to verify the feature is enabled. It does not, however, route to siblings like manage_labels for business labels, so context is clear but not fully exclusionary.

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