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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered and the description does not need to restate it. What the description adds is a field-level summary of the response (CT/T round wins, pick/ban counts), which is partly redundant with the existing output schema. It says nothing about auth, rate limits, or data freshness for a live esports source.

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?

Three tight sentences, front-loaded with the resource and return shape, followed by the required parameter and then the alternative. The only waste is the mid-sentence field enumeration that the output schema already carries.

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 single-parameter read tool with an output schema and readOnly annotations, everything an agent needs is present: what it returns, where the slug comes from with a concrete example, when to call it, and which sibling to use for per-team data.

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 description coverage is 100% and the single `slug` parameter is already documented with its source and an example. The description repeats that same guidance ("Provide slug from bo3_tournaments (for example pgl-masters-bucharest-2026)") without adding format rules or failure behavior for invalid slugs, so the baseline of 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?

The first sentence names a specific verb (Returns) and a specific resource (maps played at a BO3.gg CS2 tournament) and enumerates the returned measures (games/rounds per map, CT/T-side wins and CT win %, pick/ban counts). The final clause explicitly contrasts it with the sibling bo3_team_stats (map-pool), so the agent can distinguish the two without opening schemas.

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 states the intended use ("see which maps an event favoured") and names the alternative tool with the exact parameter value that selects it ("bo3_team_stats kind map-pool for one team"). That is an explicit when-to-use plus a routing condition to the sibling.

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