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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds useful behavioral context: data comes from the official MLB Stats API, lineups are empty until usually 2-4 hours before first pitch, and each game includes status, venue, and gamePk.

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?

Every sentence earns its place: the first identifies the resource, the second gives concrete example queries, the third describes return contents and timing behavior, and the fourth explains invocation. It is information-dense without redundancy and well front-loaded.

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?

The tool has only two optional parameters, rich annotations, and no output schema; the description compensates by listing key return fields and the lineup-timing caveat. An agent has enough context to select and invoke the tool correctly in most situations.

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?

Input schema coverage is 100%, so the schema fully documents both parameters. The description largely restates the same information (date in YYYY-MM-DD, optional team by id or name) rather than adding deeper semantic nuance, matching the baseline for full schema coverage.

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 clearly states the resource: probable pitchers and posted starting lineups per game for a date, and enriches it with concrete natural-language examples. The unique resource makes it readily distinguishable from sibling MLB tools like mlb_schedule or mlb_boxscore.

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?

Natural-language queries ('who is pitching for the Astros tonight', 'tomorrow's MLB probable starters', 'is <player> in the lineup today') make the intended use cases clear, and it explains date omission and optional team filtering. It does not explicitly contrast with sibling tools, so it stops short of a 5.

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