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

Annotations already declare readOnly/idempotent/non-destructive, so the description's added value is real: it discloses the 2-credit cost, the singles-only filter, the max 30-day cap, and the caveat that start time is present only 'where one is set'. It does not discuss pagination or result-size limits, which for a capped list tool would be the remaining useful detail.

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?

Dense but front-loaded: the use case comes first, then scope, then parameters, then cost. Most clauses carry information, though the 'Tour: atp ... on the shared endpoint pass league' sentence is convoluted and is where the schema mismatch is introduced.

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?

An output schema exists, so return shape need not be explained; the description covers scope, defaults, caps and credit cost adequately. The one completeness defect is the league/tour inconsistency, which could cause an agent to invoke the tool with an invalid argument or misjudge the default tour.

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 baseline would be 3, but the description introduces a 'tour' concept with 'atp (default) or wta' that conflicts with the schema's single 'league' enum of [tennis, wta] defaulting to tennis. There is no 'atp' value anywhere in the schema, so the text actively misleads an agent about the valid argument and the default.

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 with scope: 'upcoming matches' meaning 'every scheduled or in-progress singles match in the next N days', and lists the returned fields (players, seeds, round, start time). The 'upcoming' framing implicitly separates it from get_matches/get_player_matches, but no sibling is named, so differentiation is left partly to inference.

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?

'Use for upcoming matches' gives a clear selection context, and the 'scheduled or in-progress' qualifier tells the agent which match states qualify. There is no explicit when-not guidance or named alternative (e.g. get_matches for completed results), which keeps it below a 5.

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