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

Annotations already indicate a read-only, idempotent operation. The description goes beyond them by explaining the semantics of statsSource and explicitly warning that 'matches' totals are partial and must never be presented as career totals. This is genuinely useful behavioral disclosure.

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?

Three compact sentences: the purpose is stated first, then the statsSource field is explained, then a crucial presentation caveat is given. There is no filler and every sentence carries important information.

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 no output schema, the description takes on the burden of describing the response contents Agreement it covers key profile fields and the statsSource logic. It does not enumerate every possible response field or describe not-found behavior, but it is sufficient for a two-parameter read-only lookup.

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 input schema already documents slug and locale fully, including an example and default, with 100% schema description coverage. The description adds no parameter-level meaning beyond what the schema provides, so the baseline of 3 is appropriate.

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 specifies the resource: a player, coach, or historical figure of River, and lists concrete contents (biography, position, years, totals). It is distinguishable from siblings like get_matches or get_article by content even though no sibling is explicitly named.

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 first sentence establishes exactly when to use this tool: to fetch a profile card. The statsSource explanation and the warning against presenting 'matches' totals as career totals provide valuable context for using the result correctly, though alternative tools are not mentioned.

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