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

Annotations already declare readOnlyHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely new operational context — parallel-safe, upstream cost of 1–3, and the fact that name inputs trigger an upstream league search — which is real value beyond the structured fields.

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 core purpose, then tightly layered constraints (input forms, parallel safety, cost, example). The example payload slightly duplicates the schema's own examples, keeping it just below a 5, but there is little wasted text.

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?

An output schema exists, so return values need no explanation, and the description covers input formats, resolution behavior, cost and concurrency for a 3-required-parameter read tool. Only the absence of sibling disambiguation keeps it from being fully complete.

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%, so the baseline would be 3, but the description adds meaning beyond the schema: it explains that both athlete parameters accept slugs or names and that names resolve through the league's search, which is behavior the schema only hints at with 'slug or name'.

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+resource (head-to-head between two named athletes/fighters) and names the exact output (record and every meeting), plus scopes it to the RAF and BKFC leagues. This distinguishes it from the generic h2h_matrix/head_to_head siblings and from combat_athlete/combat_bout 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?

Gives clear invocation context: accepts slugs or names for both sides, notes that names are resolved through the league's search, and supplies a concrete example payload. It lacks explicit when-not guidance (e.g., when to prefer h2h_matrix or head_to_head instead), so it stops short of a 5.

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