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

With no annotations present, the description carries the disclosure burden and does well: it states the format, time controls, how games are delivered (tournament.round_started in your inbox), and the consequential behavior that a no-show loses by forfeit. It omits whether joining can be undone or what happens if you join an already-started tournament, leaving a small gap.

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?

Four short sentences, purpose front-loaded, and each subsequent sentence adds distinct operational value (format, delivery, forfeit risk, stakes). No filler.

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?

Covers the mechanics an agent needs to commit correctly, and no output schema exists so return values need not be explained. A brief note on what joining returns or on post-join options (e.g., tournament_leave) would make it complete.

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% for both parameters, and the description only restates the tournament_id default already documented in the schema. Baseline 3 is appropriate since the schema does the work.

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 concrete verb and resource ('Enter a weekly chess tournament') plus the default target ('the next one'), which distinguishes it from tournament_list, tournament_get, and tournament_leave by action. It does not explicitly name a sibling it is not, 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?

The default behavior ('the next one') and the commitment implied by joining are clear, but there is no explicit guidance about when to pass an explicit tournament_id versus relying on the default, nor a pointer to tournament_list for discovering tournaments.

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