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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so safety is covered. The description adds genuinely useful non-schema context: values are daily averages derived from disdex's scans rather than exact snapshots, which tells the agent not to expect precise point-in-time counts. It omits day-boundary/timezone handling and data availability for untracked servers.

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?

Two sentences, front-loaded with what is returned and scoped by time, followed by the data-quality caveat and usage examples. No filler or restatement of the tool name.

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?

For a two-parameter read tool with no output schema, the description conveys the returned measure (daily member and online counts) and its derived nature, which is enough to call it correctly. It stops short of describing the per-day record shape or behavior for servers with no scan history.

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 50%: server_id is documented and cross-references search_servers, while range has an enum and default but no prose. The description only gestures at the range parameter with "over a time window" and adds the resolution ("daily"), which is mild compensation rather than real semantics for the window choices.

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 (one Discord server) and concrete metrics (daily member and online counts) over a time window, so the agent knows exactly what comes back. It implicitly separates itself from get_stats and get_server by scoping to a single server's historical member counts, but never names those siblings explicitly.

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?

The example questions ("is this server growing?", "how big was it in March?") give clear situational triggers for selection. There is no statement of when NOT to use it, and no mention of check_invite, get_server, or get_stats as alternatives for overlapping needs.

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