mlb_get_playerGet detailed MLB player data by ID, including bio, position, and optional hydrated stats.
Get detailed player information including bio, position, and optionally hydrated stats.
| Name | Required | Description | Default |
|---|---|---|---|
| fields | No | Keys to keep (comma-separated). | |
| hydrate | No | Hydration string, e.g. "stats(group=[hitting],type=[season])" to include stats | |
| player_id | Yes | Player ID |
Changes observed during successful MCP inspections.
v1.4.1Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#"Input schema / properties / fieldsAdded value: +{
+ "description": "Keys to keep (comma-separated).",
+ "type": "string"
+}v1.3.0Input schema / additionalPropertiesRemoved value: -falsev1.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, so the safety profile is covered externally. The description adds that hydration is optional and what categories of data are returned, but says nothing about error behavior, missing IDs, or rate limits.
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?
A single front-loaded sentence with no filler; the return payload and the optional stats capability are both packed into it economically.
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 simple read tool with no output schema and fully annotated safety, the description covers purpose and payload adequately; it could note that player_id is an MLB player identifier, but the schema and required list already carry that.
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%, so player_id, fields, and hydrate are already documented, including a hydrate example. The description's mention of 'optionally hydrated stats' only echoes the hydrate parameter and adds no syntax or format detail beyond the schema.
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 (Get) and resource (player) and enumerates the payload: bio, position, optionally hydrated stats. This implicitly separates it from the stats-only sibling mlb_get_player_stats, though no sibling is named explicitly.
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?
The phrase 'optionally hydrated stats' hints that stats can be pulled through this tool rather than a stats-specific one, but there is no explicit when-to-use guidance, no exclusions, and no routing to mlb_search_players or mlb_get_player_stats.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.