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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds genuinely useful traits beyond them: 7-day retention, 200-event cap with `more`/`next` paging, messages-preview gating on the person's Messages grant, an explicit minor (under-18) exclusion, and webhook duplication. This is unusually rich disclosure of constraints an agent must plan around.

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 purpose, then constraints, then pagination — a sensible order. It is a single dense block and slightly overstuffed (the webhook note is tangential), but every sentence carries functional 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?

With an output schema present the description need not explain return shape, yet it still names the key fields and adds the operational envelope — retention window, page size, cursor loop, privacy gating. For a zero-required-parameter polling tool, nothing needed to call it correctly is missing.

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 100%, so the baseline is 3, but the description adds the cross-parameter contract the schema cannot express — that `since` must be the previously returned `next`, and how `next`/`more` drive the next call. It does not add per-parameter detail for `kinds`, `limit`, or `sphere` beyond 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 description states a concrete resource — the person's event stream — and enumerates the event payload (id, time, sphere, kind, line, ids, link), so an agent knows exactly what comes back. It references the sibling `context` as a companion cursor source but never explicitly says why an agent would pick `events` over `whats_new`/`read_unread`, so sibling differentiation is only partial.

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?

Usage mechanics are spelled out: pass `since` with the `next` from a prior call to advance, omit it to get the newest, and re-call with `next` while `more` is set. That gives a clear operating context, but there is no explicit when-to-use/when-not statement versus the many adjacent list/stream tools in the sibling set.

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