nex_mail_record_list

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

Annotations already declare readOnlyHint=true, and the description adds genuine context beyond that: expired records are included, results are cached, and the identifier to use is the local id rather than the upstream mailboxId. These are non-obvious behavioral traits an agent could not infer from structured fields.

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?

Three tightly packed sentences, front-loaded with what the tool returns and followed by the usage rule and the caching caveat. No filler, though the trailing id sentence is somewhat tangential to a paginated list operation.

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?

There is no output schema and no parameter documentation, so the description carries the full burden; it covers purpose, when to use, and caching semantics well, but leaves the pagination and filtering parameters completely unexplained. Adequate for selection, incomplete for correct invocation.

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 0% and the description explains none of the four parameters (page, size, type, keyword), including the type enum values TEMPORARY/MAINSTREAM. Worse, the 'local id vs upstream mailboxId' instruction refers to an id concept that is not even a parameter here, which can confuse rather than clarify parameter use.

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 and resource (list mailbox records) with explicit scope: current user and team, including expired ones. It also implicitly distinguishes itself from the mailbox-buying and message-listing siblings through the sign-up advice and the cached-message caveat.

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?

Gives a concrete usage trigger: 'Check here before buying a mailbox for a sign-up', which directs the agent ahead of nex_mail_buy. It also warns that an empty cached message list does not prove an empty inbox, steering the agent away from a false negative. No explicit exclusions or named alternative tool, so not a 5.

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