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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds real behavioral context beyond them: deterministic output, numbered suffixes for duplicate names, the printable-link artifact, and the goalkeeper fallback rule. It stops short of describing pagination or error conditions for invalid rosters (e.g., fewer than 7 players).

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?

Three tight sentences, front-loaded with the core action, then outputs, then edge-case rules. No filler and nothing repeated from the title or schema.

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?

With an output schema present, the description needn't explain return values, and it covers the key edge cases (duplicate names, missing keepers). For an 8-parameter tool with several conditional behaviors, it is nearly complete, though it says nothing about validation failures for out-of-range rosters or how preferred positions resolve conflicts.

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 88%, so the baseline is 3, and the description adds meaningful parameter-level behavior on top: duplicate names get numbered suffixes (players), and 'without designated goalkeepers, everyone is available in goal' clarifies how goalkeepers/canPlayGK interact. It does not explain periods, formation, gameMinutes or segmentsPerPeriod beyond what the schema already documents.

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: 'Create a deterministic rotation with balanced minutes, goalkeeper duties and preferred positions,' and names the concrete outputs (substitution windows, player minutes, printable link). It is clearly a lineup generator rather than a time calculator or formation recommender, but it never names the closest sibling (calculate_playing_time) to draw the boundary explicitly.

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?

Usage is implied by the youth-soccer framing and the conditional clauses ('Without designated goalkeepers, everyone is available in goal'), which do tell the agent how the tool behaves under different roster setups. There is no explicit when-to-use-this-vs-sibling guidance, so an agent must infer that it wants this tool rather than calculate_playing_time or recommend_formation.

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