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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds useful behavioral context beyond that: results are 'paginated' and are 'previews' (implying truncated content), plus it tells the agent where the league_id comes from. It stops short of describing page-size or return shape, but with annotations carrying the safety profile this is solid.

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, zero waste, front-loaded with the purpose followed by parameter sourcing and sibling routing. Every clause earns its place.

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?

Output schema exists so return values need not be explained, and both parameters are fully documented in the schema. For a simple two-param read tool, the description covers purpose, usage routing, and pagination behavior completely.

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%, so the schema already documents both parameters, including that league_id is 'discoverable from fotmob/leagues' and that start_index is a zero-based offset. The description's parameter notes largely restate the schema, adding only a cross-tool pointer to fotmob_leagues. Baseline 3 is appropriate.

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 ('Fetch') and resource ('paginated news previews') scoped to a FotMob league. It explicitly names the sibling tools it is not (fotmob_latest_news, fotmob_team_news, fotmob_trending_news), so an agent can distinguish it without opening any schema.

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?

Names three alternatives and the exact condition that selects each: global English feed, one team's articles, curated Trending shelf. Nothing is left to inference about when this league-scoped tool is the right choice.

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