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

Annotations already cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), and the description adds real behavioral context beyond them: signed-in players receive an email notification, and promotion becomes restricted once results exist (only americano/mexicano can take them). The final clause is cryptic, but the side-effect and constraint disclosures are genuine additions.

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 sentences, front-loaded with the core action and its trigger, and free of filler. The closing sentence ('the unstarted rounds follow the roster') is obliquely phrased and costs more parsing effort than it returns.

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?

An output schema exists, so return values need no explanation, and annotations carry the safety profile. The description covers the action, trigger, notification side-effect and a format constraint, leaving only the ambiguous roster/results clause as an unresolved gap for a mutation tool with a modest 3-param schema.

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 67% — tournament_key and request_id are documented in the schema while 'name' is not. The description adds no parameter-level meaning (it never says which argument identifies the player being promoted), so it neither compensates for the gap nor falls below the baseline appropriate to partial coverage.

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 and resource ('Move a waitlisted player onto the active roster'), with the triggering condition 'when a spot opens'. This clearly separates it from siblings like add_players, withdraw_player, remove_player and replace_player, which an agent can distinguish without opening any 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 an explicit trigger ('when a spot opens') and points to an alternative lever for a related need ('The cap can be raised with update_settings'). It does not state when not to use it, nor does it contrast against add_players for non-waitlisted players, so it falls short of a full when/when-not/alternatives treatment.

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