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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), yet the description still adds real value: ordering semantics (soonest first), the cost of 2 credits, the fact that ratings and favourites are only present 'where we rate it' / 'where one is posted', and the match-id persistence rule. The only gap is that it doesn't describe pagination or result limits, which is minor since an output schema exists.

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?

Front-loaded with the use case and return fields, then the sibling hand-off, then the credit cost and compliance boundary. The long field enumeration is dense but earns its place; the compliance sentence is slightly tangential to tool selection but is a necessary operational constraint.

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?

A read-only, zero-required-parameter listing tool with an output schema needs to convey scope, ordering, cost, and output caveats — all of which are present. Nothing an agent needs in order to call it correctly or interpret the results is missing.

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 83% and the schema already documents days (default 7, max 45), league defaults and enum values, team_id source, competition keys, and include_live default. The description implies days/live filtering through 'upcoming and live' and 'soonest first' but adds no parameter-level detail beyond what the schema provides, so the baseline of 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?

States a specific verb and resource — upcoming and live matches in every competition — and enumerates exactly what comes back (start time, teams, venue, status, ratings, favourite at median price). It also explicitly distinguishes itself from get_match by explaining that a played fixture keeps its match id and belongs to get_match instead.

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 selection rule (upcoming and live fixtures, soonest first) plus an explicit hand-off condition to the sibling get_match once a match is played. It also states a hard usage boundary — no stakes, payouts, profit calculations, bet recommendations, or sportsbook referrals — so the agent knows both when to call it and what it must not do with the output.

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