Submit Score

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

With no annotations, the description carries the full behavioral burden. It discloses the default-board fallback, but says nothing about auth requirements, whether a new submission replaces or appends to the user's prior score, or how invalid leaderboard keys are handled — significant gaps for a write operation.

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?

Two short sentences with the core action front-loaded and the conditional parameter guidance immediately after. Nothing is padded or out of order.

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?

There is no output schema and no annotations, and the three parameters are fully documented in the schema, so the description only needs to cover purpose and behavior. It does the former well but leaves out write semantics (overwrite vs. append) and auth expectations, so it is adequate rather than 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%, so the schema already documents score, userId, and leaderboardKey including the omit-for-default behavior. The description's leaderboardKey sentence largely repeats what the schema says, adding little beyond the 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 states a specific verb and resource ('Submits a score to a horizOn leaderboard for a given user'), which clearly separates it from read-side siblings like horizon_get_user_rank or horizon_get_leaderboard_top. It does not name a sibling directly, but the write action is 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?

It explains the leaderboardKey branch ('Pass leaderboardKey to target a specific board; omit it for the default board'), which is genuinely useful routing guidance. However, it gives no broader when-to-use context, prerequisites (e.g. auth), or alternatives to this tool.

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