DESTRUCTIVE: changes your real Yahoo roster positions for a given date. Provide assignments mapping each playerKey to a roster position (e.g. 1B, OF, SP, Util, or BN for bench). Players not listed keep their current slot. Defaults to your configured team and today's date. Confirm the lineup with ...
AI agents use set_lineup to create or update resources in Yahoo Fantasy Baseball — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Yahoo Fantasy Baseball environment.
| Parameter | Type | Required | Description |
|---|---|---|---|
date | string | — | Date as YYYY-MM-DD; defaults to today |
force | boolean | — | Set to true to attempt the action even though write access is not officially supported |
teamKey | string | — | Team key; defaults to configured team |
assignments | array | Yes | Player-to-position assignments |
Parameters from the server's own tool schema.
The tool modifies live roster positions in Yahoo Fantasy Baseball, which is a real write operation with meaningful consequences for the user's team. While labeled 'DESTRUCTIVE' in the description, the action (changing lineup slots) is reversible — positions can be changed again — so Write is the most accurate category.
From the tool's definition 'changes your real Yahoo roster positions for a given date' and 'Confirm the lineup with the user before calling this'
Attacks that exploit this kind of access
DESTRUCTIVE: changes your real Yahoo roster positions for a given date. Provide assignments mapping each playerKey to a roster position (e.g. 1B, OF, SP, Util, or BN for bench). Players not listed keep their current slot. Defaults to your configured team and today's date. Confirm the lineup with the user before calling this. It is categorised as a Write tool in the Yahoo Fantasy Baseball MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
set_lineup accepts 4 parameters: date, force, teamKey, assignments. Required: assignments. The full parameter table on this page comes from the server's own tool schema.
Register the Yahoo Fantasy Baseball MCP server in PolicyLayer and add a rule for set_lineup: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Yahoo Fantasy Baseball. Nothing to install.
set_lineup is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the set_lineup rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for set_lineup. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
set_lineup is provided by the Yahoo Fantasy Baseball MCP server (yahoo-fantasy-baseball-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
set_lineup is one line of Yahoo Fantasy Baseball's registry record.
The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.
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