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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the read-only nature is covered. The description adds material context beyond that: the data is sourced from a public rankings page, and the pricing model is disclosed precisely ($0.002 USDC per successful call via x402 on Base, Solana or Arc, with failed calls not charged). Rate limits and pagination behavior are not covered, keeping it below a 5.

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 core sentence is dense but informative and front-loaded with the resource and return shape, followed by the scope exclusion and pricing. The 'Related tools on this server' clause consumes roughly a third of the text to advertise two unrelated sports tools, which dilutes focus even though each remaining sentence earns its 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?

An output schema exists, so return values need no explanation, and both parameters are fully documented in the schema. The description covers source, scope, exclusions, and payment mechanics, leaving little an agent would need to infer before calling; only the practical alternative-selection story is thin.

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 description coverage is 100%, with both 'limit' (1-15, default 15) and 'division' (partial name match, default all divisions) fully documented in the schema. The description adds no syntax, format, or edge-case detail about these parameters, so the schema does the work and baseline 3 applies.

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 and resource -- reads Official UFC.com athlete rankings by division -- and enumerates exactly what comes back: champion if listed, plus ranked athletes with rank number and athlete page link. It also draws a boundary ('no fight records or per-fight stats'), which separates it from stats-oriented siblings.

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?

Usage context is implied rather than spelled out: 'Read from the public rankings page; no fight records or per-fight stats' tells the agent this is a rankings lookup, not a stats lookup. However, the only named alternatives are dev_mlb_stats and dev_nfl_stats, which are irrelevant to a UFC request; the genuinely competing siblings (dev_ufcstats, dev_espn_mma, dev_sherdog) are never mentioned, so the routing guidance mostly misses its target.

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