List Contact Accounts

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

Annotations already declare readOnlyHint and idempotentHint, covering the safety and idempotency aspects. The description adds the 'LOCAL mode only' behavioral constraint and examples of account types, but does not disclose additional behaviors such as return format or pagination. This is similar to the calibration example where description added a scoping constraint but lacked richer behavioral context.

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 that is concise and front-loaded. It communicates the core function, provides examples in parentheses, and notes the mode restriction without any waste 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 simple zero-parameter tool with an output schema available, the description is sufficiently complete. It covers what the tool lists, gives example account types, and notes the local-only constraint. The output schema presumably handles the return value details, so the description doesn't need to over-explain.

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 per the rubric the baseline is 4. The description does not need to explain parameter semantics, and the empty schema fully documents that no parameters are required.

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 the tool's function: 'Lists all contact accounts (iCloud, Google, Exchange, etc.)'. It uses a specific verb+resource construction and distinguishes from sibling tools like 'list-contacts' and 'list-contact-groups' by focusing on 'accounts' rather than contacts or groups. The 'LOCAL mode only' qualifier adds additional scope clarity.

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 a clear context for use: to list all contact accounts, with examples of account types. It also specifies a usage restriction via 'LOCAL mode only', implying it is not applicable in other modes. However, it does not explicitly mention alternatives or when-not scenarios, so it stops short of full guidance.

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