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

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavior the annotations lack: the 8-email cap and the fact that results render as an openable list. It does not say what happens on overflow or whether results are ordered.

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?

Two sentences, no filler, with the hard limit front-loaded ahead of the usage condition. Every clause carries information an agent needs.

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?

An output schema exists, so return values need no explanation, and the cap, id source, and post-search positioning are all present. Only the optional title parameter is left unaddressed, which is a minor gap for a display tool.

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 description carries the burden. It usefully documents where mail_ids come from (search_mail), but says nothing about the optional 'title' parameter or the id format beyond 'integer', leaving half the surface undocumented.

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 ('Show ... emails'), plus concrete scope ('up to 8') and output form ('a list the user can open full screen'). It implicitly separates itself from search_mail by naming it as the id source, but it never explicitly contrasts with single-mail siblings like get_email.

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?

'Use after search_mail when the user wants to see mail' gives a clear triggering context and sequence dependency. It stops short of stating exclusions (e.g., use get_email for a single message, or what to do when the user wants more than 8 results).

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