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

Annotations already cover safety (readOnly, idempotent, openWorld, non-destructive), so the bar is lower. The description still adds real behavioral context: the default and max window (5, capped at 8), the FDR scale, and crucially that an unknown club returns a view of not_found with the club list rather than an error.

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?

Dense but front-loaded: the core purpose and the two modes come first, followed by return-content details. Every clause carries information (scale, blanks/doubles, squadPlayers), though the prose is somewhat run-on for a two-parameter tool.

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 carries the full burden of describing returns, and it does so concretely for both modes: FDR per fixture, blank/double gameweeks, squadPlayers counts, last 5 results, goals for/against, clean sheets, and top 3 players. Nothing needed to call it correctly is missing.

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 the schema already documents both parameters including examples and the 1-8 range. The description's 'from the next deadline' framing mirrors the schema wording and adds little beyond it; baseline 3 applies.

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 ('FPL fixture difficulty ... from the next deadline') and clearly splits the two operating modes: without teamName returns a 20-club ticker, with teamName returns a single club's fixtures, form and top players. This is readily distinguishable from the analysis-oriented siblings.

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 when to omit teamName versus when to supply it, and what each mode yields. It also implicitly differentiates from analysis siblings by noting 'no FPLai projections, no analysis quota,' but it never names a specific alternative tool or states when not to use this one.

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