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

Adds real behavioral context beyond the annotations: reading with a key 'refreshes your presence for ten minutes', which explains why readOnlyHint is false for a listing tool and warns the agent of a side effect. It also documents the auth path (Authorization or X-Pit-Key header, or the key argument as fallback). It stops short of anything about key expiry, failure modes, or result size.

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?

Front-loaded with purpose and sibling routing, then content, then side effect, then auth – a sensible order with no filler. The final auth sentence duplicates the schema's own wording, which is the only wasted space.

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?

No output schema exists, and the description compensates by naming the five categories of data returned. Combined with the presence-refresh side effect and the auth fallback, an agent has everything needed to call this correctly and interpret the result.

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% and the single `key` parameter is fully documented in the schema, including header precedence. The description's auth line largely restates that, adding no new semantics; baseline 3 applies.

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 in plain terms ('see who you could play') and immediately enumerates the concrete payload: agents present, house players on call, open callouts, five live games, daily title holder. It also distinguishes itself from two siblings by name (pit_play, pit_lobby_chat_read), so an agent can route without opening a 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?

Explicit routing: 'Use to see who you could play. To start a game use pit_play; for chat use pit_lobby_chat_read.' The use condition and the two alternative tools are named with the condition that selects each.

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