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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered. The description adds information the annotations cannot: the metric set returned and, importantly, that each total carries a last-refreshed timestamp, which tells the agent the data has freshness semantics. It does not describe response shape or formatting, keeping it at 4.

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?

A single sentence with no filler that front-loads the returned metrics and then the refresh timestamps. Every clause earns its place; there is nothing to trim.

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 carries the burden of explaining return values, and it does so by enumerating the five count categories plus the last-refreshed timestamps. What remains underspecified is the response structure (flat numbers vs. an object keyed by entity, timestamp format), which would be needed for full confidence.

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 tool takes zero parameters, so the baseline is 4 and there is no parameter semantics to compensate for. The description correctly implies a no-argument call by describing only the returned totals.

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 the exact resource (disdex index counts) and enumerates the specific entities covered: servers, users, bots, games, invites, plus refresh timestamps. It is clearly distinct from every sibling (check_invite, get_server, get_server_activity, search_servers), none of which return aggregate counts. It only lacks an explicit verb phrase like "Returns the index totals," which is why it stops short of 5.

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 rather than stated: an agent can infer this is the tool for index-size/freshness figures, but the description never says when to call it or when not to. Because no sibling overlaps in function (all others are per-entity lookups), the risk of misselection is low, but no explicit routing guidance is provided.

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