List contact groups

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

Annotations already declare the tool read-only, idempotent, and non-destructive. The description adds valuable behavioral detail beyond that: it returns member counts, does not resolve members, and warns that resolving members would require an extra request per address book. This gives the agent useful expectations about cost and output scope.

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, no filler. The core behavior is stated first, and the important distinction from get_group is included without redundant detail. Everything earns its place.

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?

The description is complete for a read-only listing tool: it explains the return scope, the member-count behavior, and the path to get member names. The presence of an output schema reduces the need to describe return values. A minor gap is not stating what happens when address_books is omitted, but the schema already covers that.

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 input schema already documents both parameters fully at 100% coverage, including defaults, constraints, and the meaning of omitting address_books. The description reinforces the address book concept and the absence of member resolution but does not need to add more because the schema carries the weight.

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 clearly states that this tool returns groups in one or more address books along with member counts, establishing a specific verb and resource. It also differentiates itself from get_group by explicitly stating that member names are not resolved here.

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 gives clear context for when to use this tool versus get_group: use this for group listings and member counts, and use get_group when the caller wants member names. It does not enumerate all sibling alternatives, but the key distinction is explicit and actionable.

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