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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds real domain context beyond them: the -1..1 scale semantics, the events plotted on the series with team/player attribution, and the not-found failure mode for uncovered matches and non-football sports.

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, no filler, and the core value/scale definition is front-loaded before the id-handling note. Dense but each clause carries information; only the schematic listing of event types is slightly enumerative.

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 structure needn't be explained, yet the description still conveys the meaning of the return payload (scale direction, event annotations) and the failure behavior. Complete for an agent to call it correctly.

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% – the id parameter is already documented in the schema (eight-character id from a public match URL). The description only restates 'Pass a match id', adding no format or sourcing detail beyond the schema, so the baseline 3 is correct.

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?

Specific verb ('Fetch') plus a precise resource ('per-minute momentum of a Flashscore football match'), with the value domain (-1 to 1, home-positive) and plot contents stated. An agent can tell this apart from flashscore_match_stats or flashscore_match_box_score without opening a 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?

Gives a clear activation condition (pass a match id) and explicitly defines the negative case: matches without momentum coverage and other sports return not found. No sibling is named as an alternative, so it stops short of full when-not routing.

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