sleeper_get_user_leaguesFetch the NFL leagues a user belongs to for a given season; pass the Sleeper user_id and season year to get their league list.
List the NFL leagues a user belongs to for a given season. Use the user_id from sleeper_get_user.
| Name | Required | Description | Default |
|---|---|---|---|
| fields | No | Keys to keep (comma-separated). | |
| season | Yes | Season year, e.g. "2025" | |
| user_id | Yes | Numeric user id (from sleeper_get_user) |
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"
+}v1.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so safety and repeatability are covered. The description adds only the season-scoping notion, which the schema also conveys; no detail on return shape, empty results, or pagination.
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 short sentences with the core purpose front-loaded and the input-provenance hint second. No filler, nothing to trim.
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 three-parameter read tool with full schema coverage and annotations covering behavior, the description is sufficient to call it correctly. Only minor gaps remain (e.g., what a returned league entry looks like), and no output schema exists to require more.
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%, including the user_id provenance note the description repeats, so the baseline is 3. The description adds no format or constraint detail beyond what the schema already states.
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 with scope: listing the NFL leagues a user belongs to for a given season. An agent can distinguish this directionally from siblings like sleeper_get_league (league by id) and sleeper_get_league_users (users in a league), 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?
Explicitly tells the agent where the required user_id comes from (sleeper_get_user), which is actionable context for chaining calls. However it gives no when-not guidance or alternatives for other lookup directions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.