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

Annotations already declare read-only, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely non-obvious behavior: not-yet-held draws return 'pending', the widget already displays all numbers so the agent must answer in one or two sentences rather than repeating a table. It stops short of describing response shape or ordering, but that is a modest gap given the annotation coverage.

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 trigger conditions, then the return semantics, then the widget/presentation constraint. Every sentence carries a distinct instruction, though the example-phrase list makes it longer than strictly necessary for an agent.

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?

No output schema exists, and the description fully covers what comes back (the position-1 number per jurisdiction and turno, 'pending' for future draws) plus how to present it. Nothing an agent needs to call and render this tool correctly 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 coverage is 100% (baseline 3), and the description goes further by explaining the effective default of omitting jurisdiction — the widget shows the five best-known quinielas (Ciudad, Provincia, Córdoba, Santa Fe, Entre Ríos) — which refines the schema's terse 'Omit for all'. It also constrains jurisdiction to be used only when the user names specific ones.

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 (returns the cabeza — position-1 winner — for every jurisdiction and turno on a given day), and explicitly delimits itself from the sibling get_results ('For all 20 numbers of a draw use get_results'). An agent can distinguish it from the other nine siblings 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?

Provides explicit trigger phrases in the user's language ('¿qué salió hoy?', 'cabezas de ayer'), a condition for narrowing (pass jurisdiction only when the user names specific quinielas), and the alternative tool for a different need. When-to-use, when-not-to-narrow, and the alternative are all stated.

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