get_userRetrieve Sleeper user details by username or user ID. Store the user ID for future lookups since usernames can change.
Look up a Sleeper user by username or user_id. Usernames can change over time, so store user_id for future lookups.
| Name | Required | Description | Default |
|---|---|---|---|
| user_id | No | The numerical Sleeper user ID. Provide this or username. | |
| username | No | The Sleeper username (e.g. sleeperuser). Provide this or user_id. |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral transparency burden. It clearly signals a read-only lookup and adds a useful behavioral caveat about usernames changing over time. But it does not disclose response shape, not-found behavior, or what happens if neither or both identifiers are supplied.
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 compact sentences with no filler. The core lookup mechanism is front-loaded, and the user_id persistence tip earns its place as actionable guidance.
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 two-parameter read-only lookup, the description plus schema is nearly sufficient. It explains what the tool does and gives stable-identifier guidance. The main gaps are not explicitly requiring exactly one of username/user_id and not describing the return contract, but these are minor given the tool's simplicity and full schema coverage.
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?
The input schema already documents both parameters with 100% coverage. The description adds value beyond the schema by explaining that usernames are mutable and advising the agent to store user_id for stable future lookups, which directly informs parameter choice.
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 ('Look up') and resource ('Sleeper user') and clearly identifies the two lookup keys: username or user_id. This distinguishes it from siblings like get_users_in_league, which is about users within a league, and resolve_players, which is about player resolution.
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 description implies when to use the tool: when you have a username or user_id and want the corresponding Sleeper user. It also gives practical guidance to prefer storing user_id because usernames change. However, it never explicitly names alternatives or says when not to use this tool versus siblings, leaving some routing to inference.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.