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

Annotations already mark this as read-only and non-destructive, so the bar is lower. The description adds valuable behavioral context: it explains that round/time math is done by the engine, that omitting `discipline` returns a question instead of a menu, that americano and mexicano are doubles, and that no key is needed. No contradiction with annotations.

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?

The description is somewhat long but each sentence carries distinct weight: purpose, when to use, the discipline prerequisite, and a note about key requirements. It is front-loaded and structured with paragraph breaks for emphasis. Slightly dense but not wasteful.

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?

The description covers the core selection and invocation concerns: when to use, the key prerequisite, and expected output. Since an output schema exists, return values need no further explanation. The tool is sufficiently complete for an agent to choose and call it correctly, though the 'Needs no key' phrase is a bit ambiguous.

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 71%, so the schema does most of the work. The description adds important nuance about `discipline` (omitting it changes the response, it must never be inferred), but this is largely repeated from the schema's own description. Other parameters like `players_estimate` and `match_minutes` are not elaborated, so the description only partially compensates.

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?

The description clearly states the tool's function: 'Recommend tournament formats in plain language, with the round/time math done by the engine.' It also distinguishes itself from sibling tools by emphasizing it should be called FIRST for format selection, and explicitly describes the output as a `menu` to relay. The verb+resource structure is specific and unique.

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?

Explicit conditions are given: 'Call this FIRST when the organiser has not named a format, names one hesitantly, or comes from a background where americano/mexicano need explaining.' It also instructs to relay the menu text instead of asking open questions, clarifies the discipline prerequisite, and says 'Never infer it from the sport.' This is strong, actionable guidance.

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