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

Annotations only declare readOnly/openWorld/non-destructive; the description adds real behavioral context beyond them: parallel-safe fan-out, upstream cost of 1–5 via allSettled, the CS2 live path, and critically the UFC empty-board contract (section.note + emptyReason + health/lag + optional supervisor/nextCard, never fabricating match items from events[]). That empty-result semantics is exactly the kind of trait annotations cannot convey.

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?

Front-loaded one-line purpose followed by clearly labeled When to use / Prefer over / Do not use / parallel-safety / example sections. Each block adds distinct information; nothing is padded prose, and the trailing example is compact rather than redundant 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 routing (what it is not), failure/empty behavior, cost and concurrency, and per-game coverage quirks (CS2 path, UFC inclusion). With an output schema present, it need not explain return fields, and nothing an agent needs to call this correctly is missing.

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 already documents game enum, limitPerGame bounds/default, and includeLabelsOnly token-light mode. The description adds only an illustrative call ({"game":"all","limitPerGame":10}) and the "omit for all" default, which largely restate the schema. Baseline 3 is appropriate when the schema carries parameter meaning.

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+resource ("Live matches board across primary games") plus the scoping option (single game filter) and the payload shape (normalized labels, scores, matchIds). An agent can distinguish this from call_api, match_summary, and cs2_live_scoreboard 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?

Explicit when-to-use bullets ("What's live right now?", ops live strip), an explicit prefer-over rule (sequential per-game call_api live probes), and explicit do-not-use routing with named alternatives: upcoming fixtures → upcoming_schedule, historical results → match_summary. This is the full when/when-not/alternative triad.

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