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

Annotations already establish that the tool is read-only, open-world, idempotent, and non-destructive. The description adds meaningful context beyond that: the source lacks live scores, players, and odds, and the tool itself serves as a routing/orientation layer rather than a data endpoint. No contradiction with annotations.

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 dense but efficient: coverage, exclusions, conventions, routing guidance, call timing, and a concrete example are packed into a compact paragraph. Every clause adds useful orientation information with no wasted words.

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 zero-parameter informational tool with an output schema, the description leaves no ambiguity about when or why to call it. It also addresses the likely decision an agent faces—whether this source fits a query—and provides a clear example.

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 an empty input schema, so there is no parameter-semantic burden. The description explicitly notes 'No parameters,' matching the schema exactly.

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 clearly states that this tool is a source orientation guide: it covers what football-charts.com includes, what it excludes, key/season-string conventions, probability phrasing, and which sibling tool to use. This is a specific verb+resource description that differentiates it from the data-retrieval sibling tools.

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 gives explicit usage conditions: call when unsure whether the source fits a question, or once before the first call in a session. The Estonia example further demonstrates the intended call flow, ending with list_leagues.

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