set_captain

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

No annotations are provided, so the description must carry the burden of behavioral disclosure. It states that the team_id is optional and detected from account, which is a useful behavioral note. However, it does not disclose whether setting a captain is a mutation with side effects (like changing points multipliers), whether it overwrites existing settings, or the impact on future gameweeks. The description covers the basic mechanism but misses deeper behavioral context.

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 concise and front-loads the main action and optionality. It lists parameters in a clear docstring format with brief explanations. It is appropriately sized for a simple tool. Slight deduct for the literal Args: section that repeats parameter names, but overall it is well-structured.

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?

Given the tool's simplicity alert list. The output schema is present but the description does not explain the return value (e.g., success confirmation, updated team). It also does not mention constraints such as the player must be in the current squad, or that setting a vice is optional. With 0% schema coverage and no annotations, a full explanation of the effect and return is missing, making it incomplete for an agent to know what to expect.

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?

The schema description coverage is 0%, meaning the description must explain the parameters. It does provide some semantics for each parameter: player is the name of the squad player, vice is optional name, team_id is optional and auto-detected. However, it does not clarify the exact format of player and vice (e.g., must be exact matches from the squad), nor the requirement that vice must be a squad player. It also doesn't explain the implication of setting vice (does it also set vice-captain for the same gameweek?). The description adds value but leaves gaps.

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 clearly states the action (set) and the resource (captain, optionally vice-captain by name). It distinguishes from siblings like make_transfer, substitute, and play_chip which have different purposes. The scope is specific and unambiguous.

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 description implies usage (setting captain and optionally vice-captain) but does not explicitly state when to use it versus alternatives like substitute or play_chip. It does not mention any prerequisites such as having a team or being in a gameweek, nor does it note any constraints like only one captain per gameweek. The guidance is adequate but not fully explicit.

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