list_accounts

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

With no annotations, the description fully carries the burden and does so well. It discloses the return format ('Returns an array of accounts, each with id, name, email, and type fields'), a limitation ('only Exchange, IMAP, and POP account types are returned; newer Microsoft 365 account types may not appear'), and a prerequisite ('Requires Outlook to be running or returns an error').

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 concise and well-structured: purpose first, then usage context, then return format and caveats. No redundant words; all three sentences carry meaningful information.

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?

Despite no output schema, the description explains the return fields, includes an error condition, and notes a functional limitation. It fully covers what an agent needs to know to use the tool correctly, especially given its simple nature and lack of parameters.

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 the schema already covers everything (100% coverage). The description adds useful context about how the output is used (e.g., discovering account IDs), but this is beyond parameter semantics. Given the baseline of 4 for zero parameters, 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 clearly states the tool's function: 'List all mail accounts configured in Microsoft Outlook for Mac.' It uses a specific verb and resource, and distinguishes itself from siblings by noting it discovers account IDs needed by other tools like list_folders.

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?

Explicit guidance is provided: 'Use this to discover account IDs needed by other tools (e.g., list_folders with account_id filter).' This tells the agent when to select this tool versus alternatives, and the mention of mail accounts differentiates it from other list tools like list_calendars.

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