Players

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

Annotations already cover read-only/idempotent/non-destructive safety, so the description's job is to add behavioral context — and it does, disclosing that online=true switches to a live-state view returning world, game mode, health, food, level, ping, idle time and location. It doesn't state whether the roster is paginated or how far back 'has played' reaches, which would have made it 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?

Two dense sentences with no filler, front-loaded with the resource scope and followed by the field list and mode flags. The second clause is somewhat run-on, stacking two distinct behaviors into one sentence, but nothing is wasted.

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 and no annotations about return shape, the description correctly spends its words enumerating the returned fields for both the default and online views, which is the main thing an agent needs. It omits default sort order and pagination behavior, but those are covered by the schema's cursor parameter.

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?

Against 75% schema coverage, the description still earns credit by explaining the non-obvious semantics of limit=0 (count-only) and online=true (switches the entire result shape), which go beyond the schema's terse hints. The sort enum values and cursor mechanics are left entirely to the schema, keeping it out of 5 territory.

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 resource precisely ('Everyone who has played here') and enumerates the core fields (online state, first/last seen, playtime), which is more specific than the bare name. It implicitly separates itself from the singular get_player by scoping to 'everyone', but never names a sibling explicitly, so it stops short of full differentiation.

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 clear conditional guidance: 'limit 0 only counts them' and 'online true lists who is playing now instead', directly telling the agent which mode to pick for counting vs. live status. It stops short of a 5 because it offers no exclusions or named alternatives (e.g. use get_player for one player's details).

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