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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds context annotations cannot carry: results are marked `untrusted_content: true` because subjects/addresses are mail-derived, which is important behavioural information for an agent handling the output. It stops short of describing ordering across modes or pagination behaviour beyond the limit default.

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?

Front-loaded with the purpose, then the mode semantics, then the untrusted-content caveat, then the sibling handoff — a sensible order with no filler. It is dense (three sentences packed with clauses) but every clause carries 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?

With an output schema present, return shape needn't be documented, and the description still flags the untrusted-content marking, which an agent must know. Combined with the mode semantics and the pointer to `reminder`, an agent has what it needs to call this correctly; only cross-sibling list disambiguation is absent.

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 100%, so the baseline would be 3, but the description genuinely enriches the `show` parameter by defining what 'due', 'upcoming' and 'all' actually return, including that 'all' includes finished items. It adds nothing for `kind`, `inbox`, `inbox_id` or `limit`, which are left entirely to the schema.

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 first sentence states a specific verb and resource ('List the follow-ups and snoozes the server tracks'), immediately scoping the tool to two reminder kinds. It also distinguishes itself from the sibling `reminder` tool by noting that `reminder` takes an id from this list to mutate a record, so an agent can route without opening either schema.

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 explains the three `show` modes and what each surfaces ('due' = past due with no reply plus failures; 'upcoming' = pending, soonest first; 'all' = everything, finished included), which is genuine selection guidance. It also hands off to `reminder` for mutation, but does not contrast with adjacent list siblings such as `schedule_list` or `draft_list`.

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