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

With no annotations, the description carries the full burden and does well: it discloses the post-entry lifecycle (round robin at start, matches surface in your games, playable from anywhere) and the reversibility window (withdraw only before start). It omits whether entry is free, capped, or what confirmation is returned.

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 with the default and the lifecycle front-loaded and the escape hatch (withdraw_tournament) placed last. No sentence is 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?

For a zero-required-parameter tool with no annotations and no output schema, the description covers the action, the default, the consequence of entering, and how to reverse it. It stops short of covering failure modes such as no open tournament or an already-started tournament.

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 both parameters are documented there, so the baseline is 3. The description does add one piece of meaning the schema lacks — the default behavior when tournament_id is omitted — but the token parameter gets no added context.

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 (enter) and resource (scheduled tournament), and defines the default target ('the next one open for sign-up'). An agent can distinguish this from list_tournaments and withdraw_tournament without inspecting either 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?

Gives clear context for when to use it (sign-up window) and routes the inverse operation to withdraw_tournament, which must be done before the start. It does not spell out eligibility or what to do if no tournament is open, so it falls short of full when/when-not coverage.

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