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

The annotations already declare readOnlyHint=true and destructiveHint=false, and the description adds the behavioral note that the returned accounts are connected and usable as a from_account_id. It does not describe return format, pagination, or rate limits, so it adds only marginal extra context beyond those annotations.

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 front-loaded, with the core action in the first clause and a brief, non-repetitive usage note in the second. Every word adds value and there is no filler.

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 tool is a simple list with no output schema, and the description gives enough to know the end use, but it does not mention pagination (page/size) or describe the shape of the returned accounts. For a tool that could return several connected accounts, this is a moderate gap.

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 description coverage is only 33% (only 'id' is described), and the tool description does not mention the 'page' or 'size' parameters at all. The description adds the term 'connected mail accounts' but that largely reiterates the purpose rather than explaining the meaning of each input, so it does not compensate for the low coverage.

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 names the verb 'List' and resource 'a user's connected mail accounts', and it distinguishes this from the sibling hire list for company mail accounts by specifying the user scope. The title and context signals also reinforce the purpose.

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 explicit usage context by stating the accounts can be used as a 'from_account_id' when sending messages. However it does not name alternatives or list when not to use this tool, though the user scope in the description implies the separation from company-level lists.

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