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

Beyond the readOnlyHint and openWorldHint annotations, the description discloses important behavioral nuances: the empty-list semantics between tournaments, the tournament_not_found error for unrecognized keys, and the normalization across the priced field. This significantly helps the agent anticipate edge cases.

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 well-structured and front-loaded with the core purpose, followed by usage instructions and edge cases. While it is a bit lengthy, each sentence contributes meaningful information. The 'Read-only' sentence is redundant with the readOnlyHint annotation, but this is a minor deduction.

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 is complete for this tool's complexity: it covers the two call patterns, error behavior, and the distinction from the sibling soccer tool. Since an output schema exists, the description does not need to explain return values, and it fully leverages the schema and annotations.

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?

The schema already covers the parameter with 100% coverage, but the description adds essential context: the value must be taken verbatim from a no-argument call to the same tool, omitting it lists tournaments, and it explicitly clarifies this is not an API key. This goes beyond the schema's basic 'Identifies one tournament' description.

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 lists golf outright-winner probabilities and can retrieve a specific tournament by key. It specifies the verb 'list' and distinguishes from sibling list_tournament_outrights by explicitly stating 'GOLF ONLY' and naming the alternative for soccer.

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 when-to-use guidance: call with no arguments to list tournaments, call with tournament_key to get a single tournament. It also names the alternative tool for soccer competitions and clarifies that an empty list means no tournaments are priced rather than an error.

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