mail_messages

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

With no annotations, the description carries the full burden. It usefully discloses that 'orderId acts as the secret', i.e. an auth/access mechanism, and that the call is free. It still omits what the mail payload looks like, volume, or pagination behavior.

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?

Very short and front-loaded, but the trailing '(free)' is duplicated verbatim, which is sloppy and wastes one of only two clauses. The core fact is stated first, which is good.

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 minimal one-param, no-output-schema tool this is thin. A reader cannot tell how it relates to 'mail_inbox', what constitutes a valid orderId, or what the response contains.

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 coverage is 0%, so the schema only names 'orderId' as a string with no meaning. The description compensates by explaining that orderId serves as the secret, adding real semantic value beyond the bare schema, though it doesn't specify the identifier's source.

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?

States a specific verb ('Read') and resource ('mail an inbox received'), so the basic action is discernible. However, it fails to distinguish itself from the sibling 'mail_inbox', leaving ambiguity about which of the two mail tools to pick.

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?

No when-to-use guidance, no prerequisites, and no mention of when to prefer this over 'mail_inbox'. The parenthetical 'free' hints at cost, but no explicit selection guidance is offered.

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