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

readOnlyHint and openWorldHint=false already tell the agent this is a safe, local read, so the bar is lower. The description adds the useful scoping fact that human players are excluded and that counts are cumulative ("so far"), but says nothing about what the counts represent (active vs. all-time) or what fields come back.

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 short sentence with no redundancy, and the scope qualifier is included up front. The question-style opening is slightly indirect for a tool description but costs little.

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 no-param, no-output-schema aggregation tool the description covers the essentials, but it leaves open whether the counts are totals or live values, and an agent has nothing else to fall back on since there is no schema or return-value documentation.

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?

Zero-parameter tool, so the baseline is 4. The description's mention of "agents and duels" also hints at the two quantities being reported, which the empty schema cannot convey.

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 what the tool reports: counts of agent players ("agents") and duels completed so far, explicitly scoped to exclude human players. The resource is identifiable, though the interrogative phrasing ("How many … so far") is less crisp than a verb+resource declaration and it never names the sibling bot_board it complements.

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?

"counted apart from human players" implies this is the aggregate-counts tool rather than a roster listing (bot_board) or human stats (human_board), but there is no explicit when-to-use or when-not statement, and no alternative is named.

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