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

Annotations already cover the safety profile (readOnlyHint, openWorldHint), and the description adds real behavioral context: result ordering (upcoming first, past included where listed), fixed page size of eight, cursor-based continuation, and a stated cost of 1 credit. Rate limits or failure modes for private/removed pages are not mentioned, keeping it short of a 5.

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 short sentences, all load-bearing: what it returns, how it orders and paginates, and what it costs. The key scoping and ordering facts are front-loaded with no filler.

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 no output schema, the description steps in to describe the returned fields (start time, place, host, cover photo) and the pagination model, which is what an agent needs. The only gap is the undocumented cache_max_age parameter and no hint about empty results for pages without events.

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?

The description reinforces cursor semantics ('pass pagination.cursor back for the next eight'), tying it to the page size rather than merely restating the schema. Url forms and cursor were already covered by the schema (67% coverage), but cache_max_age remains undocumented in both places, so it is not fully compensated.

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+resource and narrows scope: events hosted by a public Facebook Page, ordered upcoming-first. That distinguishes it in practice from facebook_event (a single event), facebook_eventsSearch (search) and facebook_cityEvents (city-based), though no sibling is named explicitly, so an agent must infer the boundary.

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 is implied by the 'public Facebook Page' scoping and the pagination instruction, but there is no explicit when-to-use / when-not guidance, e.g. no note that event *search* belongs to facebook_eventsSearch or that cities belong to facebook_cityEvents. The agent has to derive the routing itself.

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