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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, covering the safety profile. The description adds the useful context that predictions depend on the user's plan ('when available on your plan'), which is behavioral information not in the annotations. It does not describe error cases or rate limits, but the annotation coverage lowers the bar.

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 sentence plus an example, with the core purpose stated first and example code demonstrating usage. Every element is useful, and it avoids redundancy with the schema. This is a model of conciseness.

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 tool with three fully documented parameters and no complex output schema, the description adequately conveys the purpose, required inputs, and dependence on plan availability. It does not mention pagination or error handling, but these are not critical for this tool, and the annotations already cover safety and idempotency.

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 all three parameters are already documented. The description reiterates that matchId is required and gives an example usage, but it adds no semantic meaning beyond the schema. It does clarify that sport defaults and aliases are handled, which mirrors the schema, so the 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?

The description clearly states the tool returns match predictions (win/draw/away probabilities), specifying the resource (match) and the nature of the output. It does not explicitly differentiate from sibling tools like highlightly_highlights or highlightly_matches, but the purpose is unambiguous enough for an agent to understand what it does.

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 provides an example with parameters and states that a match ID is required, but it offers no guidance on when to use this tool versus alternatives (e.g., highlightly_matches for listing matches, highlightly_highlights for video highlights). It does not mention exclusions or alternative conditions. The example is helpful but not a substitute for explicit routing guidance.

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