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

Goes well past the supplied readOnlyHint/openWorldHint: names the upstream data source (ESPN public site JSON), states that times are UTC and that scores match the MLB Stats API for final games, and — most importantly — discloses a real cost of $0.002 USDC via x402 only on successful calls. That pricing and failure-charge behavior is exactly the kind of thing an agent can't infer from annotations.

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-loads the purpose and output fields, then the alternatives and pricing—a sensible order. The sibling sentences redundantly restate the sibling titles ('for one date: every game with away') which costs a few words but doesn't obscure the core message.

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?

With an output schema present, return shape needn't be described, and the description still covers source, timezone, cost, and date default. It doesn't say what happens on a date with no games or whether empty days are billed, a minor gap for a paid single-param tool.

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 the schema already documents the date format and the 'yesterday UTC' default. The description reinforces the date scope and UTC convention but adds no new semantics such as timezone handling for non-UTC dates beyond the default.

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?

Names a specific resource and scope ('ESPN MLB scoreboard for one date') and enumerates the returned fields (away/home team, score, status values, venue), so an agent knows exactly what it yields. It explicitly distinguishes itself from the NBA and NFL scoreboard siblings.

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?

Explicitly routes a different-need agent to dev_espn_nba_scoreboard and dev_espn_nfl_scoreboard, and clarifies the countdown correctly. But those alternatives aren't the riskiest confusion—other MLB tools on the server (dev_mlb_stats, dev_mlb_statsapi, dev_baseball_reference) aren't addressed; the 'Scores match the MLB Stats API for final games' line partially mitigates but isn't framed as guidance.

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