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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, but the description adds substantial context beyond them: the 31-day maximum span, inclusive date semantics, default 50 and capped 100 event types, cursor-following behavior for events_page.next_cursor, and the warning that missing or null never means zero. It also sets expectations that the response is dynamic and is 'evidence, not a server-generated conclusion', which is exactly the interpretive guidance annotations cannot carry.

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?

Purpose and the 'start here' routing rule are front-loaded, and nearly every sentence carries a distinct constraint. The one crowded passage is the dynamic-JSON sentence, which chains schema_version, period, freshness, sample sizes, unknown fields and null semantics into a single run-on clause, making it slightly harder to parse than the rest.

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?

There is no output schema, so the description must describe the return surface — and it does, listing the metric families, the metadata fields to inspect, and the events_page.next_cursor pagination token. Combined with the date-span limit and pagination policy, nothing an agent needs to call this 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 coverage is 100%, so the baseline is 3, but the description adds real meaning the schema does not: that dateFrom and dateTo are inclusive calendar dates and may span at most 31 days, and that eventLimit defaults to 50 and is capped at 100. The only mild gap is that eventCursor's relationship to the return payload is covered but the shape of events_page itself is only alluded to.

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 names a specific verb and resource ('Compact overview of one game's preaggregated telemetry') and enumerates exactly what is included: volume, event inventory, sessions, users, duration and freshness. It explicitly distinguishes itself from the sibling drill-down tools (event, timeseries, session-facts), so an agent can choose correctly without opening any 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?

It gives an explicit ordering rule ('Start here, then call the event, timeseries or session-facts tool only for the question you need to answer') plus a clear prohibition ('do not fetch every page preemptively') and a prerequisite ('Read get_game_telemetry_guide before instrumenting a game or interpreting this response'). Both when-to-use and when-not-to-use are stated, and the alternatives are named.

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