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

Annotations already declare readOnlyHint and openWorldHint=false, and the description adds genuinely useful traits on top: oldest-first ordering, cursor round-trip semantics, the conditional nature of next_cursor, the enumerated event types, and forward-compatibility guidance ('ignore types you do not know'). That last point is non-obvious and prevents an agent from erroring on unknown events.

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 dense sentences, front-loaded with what the tool returns, followed by how to paginate. Every clause carries operational meaning; nothing is filler or restatement of the title.

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 shape needn't be described, and the description covers the tricky parts (cursor protocol, ordering, event types). It omits any mention of the limit parameter or default page size, which is a minor but real completeness gap for a sync/audit 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 must carry the load, and it does for two of three parameters: group_id omission means all groups, and since is a cursor fed from next_cursor (clarifying the ^\d+$ pattern). The limit parameter and its 1-100 bound are never mentioned, leaving one gap.

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 ('Events of a group... since a cursor, oldest first') and immediately defines scope via group_id omission (all groups when omitted). This is clearly distinguishable from siblings like get_group, list_expenses, or get_inbox, which return current state rather than an event stream.

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?

It explicitly names two use cases ('serves to sync and as the audit log') and gives precise re-invocation guidance: pass next_cursor as since, and next_cursor is set only when more events are waiting right now. It does not name alternative tools or state when not to use this one, so it falls just short of a 5.

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