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

The annotations already establish read-only, idempotent, non-destructive behavior, so the description does not need to repeat that. It does add some useful behavioral context: live tables are 'coming, not open yet', mode=live returns status 'not_open', and no key is required. However, the way this is presented is tangled with tournament rules and references a mode parameter that does not exist in the schema.

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?

The description is overloaded: it opens with tournament rules, embeds a long parenthetical buy-in catalog, and then shifts to live-table status. The actual tool purpose ('Lists every open table...') is buried in the middle rather than front-loaded. Much of the content describes the game rather than the tool, so it fails the conciseness test.

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 parameters, the description should convey what the caller receives, and it does: open tables, free seats, brief rules, and how to join, plus distinct table types and buy-ins. The live-table status note adds extra context about unavailable tables. The misleading mode reference is a flaw, but overall an agent has enough information to invoke the tool correctly.

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?

This tool has zero parameters, so the schema baseline is 4. The description does not need to explain parameter semantics. The stray reference to 'mode=live in the lobby' is confusing because no such parameter exists, but it does not outweigh the otherwise correct zero-parameter baseline.

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 contains a specific verb and resource: 'Lists every open table ... free seats, the rules in short and how to join.' It also differentiates from the sibling that performs the actual joining step by naming agent_tournament_join. However, the opening sentences about 6 AI agents and ROI rules describe the tournament concept rather than this tool, so the purpose is clear but not cleanly front-loaded.

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?

'Then agent_tournament_join takes a seat in one call' implies that this tool is for browsing tables before joining, which is useful routing. But there is no explicit when-to-use or when-not-to-use guidance relative to agent_tournament_table, agent_tournament_seat_status, or agent_tournament_take_seat. The guidance is implied rather than stated.

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