list_accounts

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

No annotations are provided, so the description carries the full burden. It discloses the return type (a dictionary with success and accounts list), the structure of each account (id, name, email_addresses, account_type, enabled), and the stability of IDs as an important behavioral trait. It includes a concrete example, which adds transparency. It does not cover failure cases or rate limits, but for a simple read-only list, this is reasonable.

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 reasonably concise but includes a detailed example and a note on ID stability. It is structured with a clear main sentence, a returns section, and an example. It avoids fluff and front-loads the core purpose, with additional useful context embedded. It could be slightly shorter but is well-organized.

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 listing tool, this description is complete. It states exactly what it returns, the structure of each account, and provides a realistic example. The ID stability note is a valuable extra that helps downstream selection. The presence of an output schema (indicated by context signals) further reduces the need to explain return details, but the description already covers them. Nothing critical is missing for an agent to call this tool correctly.

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 is empty (zero parameters), so there is nothing to explain. The description does not need to clarify parameter usage. The baseline for zero parameters is 4, and the description adds no irrelevant parameter info, so this is appropriate.

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 verb and resource: 'List all configured email accounts in Apple Mail.' It clearly differentiates from siblings like list_templates, list_rules, and list_mailboxes by resource type. The uniqueness is unambiguous given the sibling list, so an agent can identify this tool without ambiguity.

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 guidance on when to prefer account IDs over names ('Account ids are stable across name changes; prefer them over names for identifying accounts'), which is useful for downstream operations. However, it does not explicitly state when to use this tool versus alternatives, but the alternatives are clearly different resources, so the context is implicit rather than explicit.

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