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

The annotations already cover safety and idempotency: readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false. The description adds useful behavioral context by stating that the tool returns all 20 clubs, that the data is 'verified' and scoped to 2026/27, and which fields are included, though it does not describe refresh cadence or formatting.

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?

The description is a single, front-loaded sentence with no filler. It states the core action, scope, season, and returned attributes efficiently.

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, read-only directory tool with no parameters and no output schema, the description is complete enough. It specifies the number of records, the season, and the fields returned, giving the agent what it needs to decide whether to call the tool.

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 tool has zero parameters and the schema is empty, so there are no parameter semantics to explain. The baseline for a zero-parameter tool is 4, and the description does not need to add parameter guidance.

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 uses a specific verb and resource: 'List all 20 Premier League clubs.' It names the season and the exact attributes returned, so the agent can distinguish this directory tool from statistical or lineup-focused 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?

Usage is implied by the tool name and the phrase 'List all 20 Premier League clubs,' but the description does not explicitly state when to use this tool versus siblings. It also does not address the overlap with get_set_piece_takers despite including 'set-piece specialists' in the returned fields.

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