mlb_get_team_rosterFetch an MLB team's roster with player names, positions, jersey numbers, and status to check active, full-season, or depth chart lineups.
Get a team's roster with player names, positions, jersey numbers, and status.
| Name | Required | Description | Default |
|---|---|---|---|
| fields | No | Keys to keep (comma-separated). | |
| season | No | Season year | |
| team_id | Yes | Team ID | |
| rosterType | No | Roster type: active, fullSeason, 40Man, depthChart, etc. | active |
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, idempotentHint, and openWorldHint, covering the safety profile completely. The description adds only output content, not behavior: it says nothing about what rosterType changes, how season defaults behave, or whether the result is filtered or paginated.
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 verb and resource come first and the output fields follow. It is efficient, though it stops short of any additional routing or scoping detail.
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 no output schema, the description partially compensates by listing returned fields, and annotations plus a fully documented schema cover safety and inputs. Missing context includes what 'status' means and what the non-default rosterType values return, which an agent calling this tool would reasonably want.
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 all four parameters are documented in the schema and the baseline is 3. The description adds no parameter-level meaning, notably omitting that rosterType defaults to 'active' and accepts values like fullSeason, 40Man, and depthChart.
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 ('Get a team's roster') and enumerates the returned fields (names, positions, jersey numbers, status), so it is clearly distinguishable from mlb_get_teams or mlb_get_player. It does not, however, explicitly contrast itself with the near-identical nhl_get_team_roster or other sibling roster tools.
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?
There is no when-to-use guidance, no prerequisites (e.g., that team_id must come from mlb_get_teams), and no mention of alternatives such as mlb_get_player for individual players. The agent must infer usage entirely from the name and schema.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.