Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare this as a read-only, idempotent, closed-world operation, so the safety profile is covered. The description usefully adds that behavior branches on team_id (own squad ranking vs. global best options), but says nothing about freshness, data scope beyond the gameweek, or return shape.

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 sentences, both earning their place, with the use trigger front-loaded and the parameter-dependent behavior immediately following. No filler.

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 a single optional parameter, full schema coverage, and rich annotations, the description supplies the one thing structure cannot: the semantic difference between the two call modes. Absent an output schema it could say slightly more about what the ranking contains, but it is adequate for correct invocation.

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 coverage is 100% and the schema already explains that team_id accepts an entry ID or a URL containing /entry/<id>/. The description goes beyond that by stating what providing or omitting the parameter actually changes in the output.

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 names a specific verb-and-resource pair — recommending who to captain in FPL for the current gameweek — and clarifies the tool's two output modes. It does not explicitly differentiate itself from siblings like get_player or get_my_team, but the purpose is unambiguous.

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 opening clause gives an explicit trigger ('when someone asks who to captain... this gameweek'), which is a clear use condition. It stops short of naming alternatives to use instead or exclusions, so it does not reach the 5 level.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.