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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered; the description adds the source origin (official UFC.com athlete page) and, importantly, billing behavior: $0.002 USDC per successful call via x402 on Base/Solana/Arc, with failed calls not charged. That cost-and-failure disclosure is real value beyond annotations, though rate limits, latency, and what happens with an unresolvable fighter are unstated.

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 resource scope and the input instruction are front-loaded, which is good, but the middle is a long comma-run enumeration of return fields that largely duplicates the existing output schema, and the sibling sentences are formulaic and partly garbled ('odds screens: every listed'). Length is defensible for a rich payload, yet several clauses do not earn their place.

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?

For a single-parameter read tool with an output schema, annotations, and disclosed pricing, the definition covers source, scope, cost, and sibling alternatives — enough to call it correctly. The gap is edge behavior: unknown fighter names, missing divisions/rankings, and data freshness relative to the live UFC.com page are not addressed.

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% and the single parameter already carries its own description with a slug example ('islam-makhachev'). The description restates the same name-or-slug duality and adds no format hints (case sensitivity, how to handle ambiguous names, whether partial names resolve), so it matches the baseline for a fully documented schema.

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 states a specific verb-free but unambiguous resource: a UFC fighter career profile sourced from the official UFC.com athlete page, and enumerates exactly what comes back (record, strikes, takedowns, averages, bio, recent bouts). It explicitly distinguishes itself from dev_sherdog (Sherdog profiles) and dev_covers (sportsbook odds), so an agent can pick it without opening the 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?

It gives the invocable condition up front ('Give the fighter's name or UFC.com slug') and routes two adjacent needs to siblings. It does not address the harder ambiguity an agent faces with this server — e.g. dev_ufc_stats or dev_espn_mma for MMA data — so the exclusions are partial rather than complete.

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