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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds that it pulls from the 'official MLB Stats API' and lists the fields, but doesn't disclose any additional behaviors like rate limits, error cases, or data freshness. Given the annotations, this is adequate but not above the baseline.

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?

Two sentences, zero filler. The first sentence front-loads the purpose and the returned fields, the second gives usage alternatives. Every clause earns its place.

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 single-parameter tool returning biographical data, the description fully covers what the agent needs: what it returns, how to use alternatives for stats, and the source. No critical information is missing for correct invocation.

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 description does not add extra meaning about person_id beyond what the schema already provides ('MLB person/player id (e.g. 660271)'). It is a single parameter with clear documentation in the schema, so the description doesn't need to expand further.

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 specific verb ('Returns') and a clear resource ('Player biographical profile from the official MLB Stats API'), enumerating the exact fields returned. It also explicitly differentiates from siblings by naming mlb_player_stats, mlb_player_game_log, and mlb_matchup for other data types.

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?

Provides explicit routing: 'For season statistics use mlb_player_stats; for per-game form use mlb_player_game_log; for batter-vs-pitcher history use mlb_matchup.' This tells an agent exactly when to pick this tool and when not to.

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