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

With readOnlyHint and openWorldHint already supplied, the description still adds real value: per-call pricing ($0.002 USDC via x402 on Base/Solana/Arc), the fact that failed calls are not charged, the upstream source (public results page), and a coverage caveat that only matches listed for that day are returned. It stops short of noting rate limits, latency, or output size, so it is strong but not exhaustive.

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?

Purpose, returned fields, day scoping, alternatives, and pricing are ordered sensibly with the core capability front-loaded. The dev_bundlephobia clause (npm package bundle size) is unrelated filler that dilutes the sibling-routing section and costs a point.

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 two-optional-parameter read tool with an output schema and safety annotations, the description covers source, scope, cost, and fallback tools, which is nearly everything an agent needs to decide and call. It repeats return fields the output schema already defines and omits any note on result volume or failure modes, but nothing essential 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 description coverage is 100%, and the schema already documents the date format, its default (yesterday UTC), and the full tour value list including the default. The description adds only the indirect 'only matches listed for that day' scoping note and no extra meaning about date timezone handling or tour selection behavior, so the baseline 3 applies.

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 concrete verb+resource ('match results for one day' from TennisExplorer's public results page) and enumerates the return fields (tournament, start time, players with seed, sets, set scores, odds), which is far more specific than the title. It differentiates itself from dev_flashscore, but not from the closer tennis siblings (dev_sofascore_live, dev_wta_tennis_rankings), leaving some ambiguity about which tennis source to pick.

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 gives explicit routing for two alternatives with their selection conditions ('dev_flashscore when you need Flashscore match list for one sport and day: every match'), which is genuine when-to-use guidance. It never states the condition that selects this tool over the other tennis/scoreboard siblings, nor any when-not-to-use exclusion, so it falls short of a full 5.

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