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

readOnlyHint=true already covers the read-only trait; the description adds substantial context beyond it: 'Costs no API quota' (cost behavior), 'A listed sport may have no fixtures today' (availability caveat), and 'each product serves only its own provider' (scoping constraint). No contradiction with the annotation.

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?

Four sentences, each earning its place: purpose, quota cost, data caveat, and sibling routing. The core purpose is front-loaded in the first sentence, and the closing 'which sport ids exist, not what is live' reinforces the scope without redundancy.

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-parameter, read-only enumeration with no output schema, the description covers everything needed: what is returned (sport ids), how the output is used (sport= filter), cost behavior, provider scoping, and the correct sibling for live data. Nothing an agent needs to call it 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?

With zero parameters the baseline is 4, and the description earns it by explaining the downstream use of the returned values — 'so a sport= filter is never a guess' — which tells the agent how the output is consumed. Trivial 100% schema coverage for an empty schema adds nothing, so the filter-usage hint is the only semantic value, and it is genuinely useful.

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 the resource and result — every sport id the wire understands — and closes with an explicit contrast: 'Answers "which sport ids exist", not "what is live"'. It names and differentiates the sibling get_coverage directly. The only minor opacity is the unexplained domain term 'wire', which does not obscure the core purpose.

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 explicit routing: 'use get_coverage for what is actually on the board' and warns each product serves only its own provider. It also clarifies when not to use this tool — it answers existence, not live status. No inference is required to choose between this and alternatives.

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