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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description adds useful context beyond that: 'Works on the FREE plan (no card needed)' and the data-quality nuance that some fields are included 'where curated.' This helps with access and expectations in a way annotations do not.

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 uses three short sentences with the central purpose first, then return fields, then the plan note. It is efficient and front-loaded, though some of the field list could arguably be left to the output 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 one well-specified parameter, clear source for the ID, plan info, and visible output schema, the description is complete enough for an agent to invoke the tool correctly. A small gap is that it does not describe the behavior when a tournament_id is missing or not found, but that is a minor omission.

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% for the single parameter, so the description has no burden to document the parameter. It only repeats what the schema says ('stable tournament id', carried on match objects) without adding format, validation, or additional semantic detail.

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 plainly states the verb ('stable id') and resource ('tournament'), explains where the ID comes from, and lists the fields returned, distinguishing it from sibling tools like search_tournaments. An agent can immediately understand this is a single-entity fetch, not a search.

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?

The description gives clear context for when to use it: you have a stable tournament_id, e.g., from a match object. The input schema adds that the ID can also come from search_tournaments. It does not explicitly tell the agent to use search_tournaments instead when only a name is known, but the intended use is easily inferable.

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