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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds genuinely useful behavior beyond that: what the result contains (alternatives plus coaching notes), the format-over-age precedence rule, and the balanced-7v7 fallback.

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 tightly packed sentences: the value proposition first, then the precedence/default rules. No filler, and the highest-value constraint (format precedence) is front-loaded.

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 values need not be explained, and the description already characterizes them briefly. For a no-required-param, read-only computation tool, everything needed to call it correctly is present; only the semantics of the style enum are unstated.

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 67% and the description compensates well: it maps formats to age ranges, documents the default for both format and style ('balanced 7v7'), and supplies the cross-parameter precedence rule that the schema cannot express. The 'style' enum's meaning (attacking/defensive emphasis) is left implicit, which is the only real gap.

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 (choose/recommend) and resource (formation), and pins down the exact decision space with the 7v7/9v9/11v11 age mapping. The resource is clearly distinct from siblings like generate_fair_lineup or calculate_playing_time, though it never names a sibling 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?

Gives the applicable conditions (age/format bands), an explicit precedence rule ('explicit format takes precedence over age'), and the default behavior when nothing is supplied. It stops short of stating when NOT to use it versus the lineup/playing-time siblings, but the operating context is clear.

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