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

Annotations already declare readOnly and openWorld, so the bar is lower; the description still adds real value by disclosing the paid x402 billing model ($0.002 USDC per successful call, failures not charged) and the copyright restriction. Minor omission: no rate-limit or pagination behavior, though a single-date query makes that largely moot.

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 with what the tool returns, then scope, then date semantics, then cost. The pricing sentence is long but earns its place for an x402-paywalled tool; the copyright sentence is the only borderline 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?

An output schema exists, so return shape needn't be spelled out, and the description covers scope, date interpretation, source, and payment semantics. The one gap is the absence of any sibling differentiation in a crowded MLB/baseball tool family.

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 100% schema coverage the baseline is 3, and the description earns above that by clarifying that the date is the schedule date and that game times are UTC — a distinction that changes interpretation of the parameter beyond the schema's 'default: yesterday UTC'.

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 specific verb and resource ('MLB games for one date'), names the authoritative data source (official MLB Stats API), and enumerates the returned fields (teams, scores, status, venue, inning). It does not explicitly contrast itself with close siblings such as dev_mlb_stats or dev_espn_mlb_scoreboard beyond the source-API implication.

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?

Usage is implied by the scope ('regular and postseason games as the schedule lists them'), which tells an agent this is a schedule-driven slate lookup. However, there is no explicit when-to-use or when-not statement, and no routing guidance toward the several near-identical MLB/baseball siblings.

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