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

Annotations already declare readOnly, idempotent, closed-world, and non-destructive, so the safety profile is covered. The description adds genuinely non-obvious behavior: a 5-credit cost, that career rate stats are UFC-only, and that ufc_record mirrors record for the UFC and is null elsewhere. Missing only pagination/response-shape notes, which the output schema covers.

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 use case, then a single dense enumeration in which each clause conveys distinct content (fields, scope caveats, cost). It is long but nearly every clause carries information; the parenthetical about ufc_record is the only mildly awkward insertion.

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 2-parameter read tool with a full output schema, this covers the important gaps: cost, promotion-specific nullability, and UFC-only stat coverage. Only the relationship to sibling tools for id lookup and extended fight history is left unstated.

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 both parameters are documented in-schema, including the league enum values and default. The description adds no parameter-level guidance beyond what the schema says (the ufc_record note concerns output, not inputs), so the 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 resource ('one fighter's profile') and enumerates exactly what the payload contains: biographical fields, record by method, per-15-minute career rates, ratings, and last five fights. That level of detail makes it distinguishable from get_fighter_fights (full fight list) in practice, but it never names a sibling tool, so it stops short of a 5.

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?

'Use for one fighter's profile' gives an implied usage context but no when-not guidance, no prerequisites, and no pointer to alternatives such as search_fighters for resolving an id or get_fighter_fights for full history. The reader must infer selection from the enumerated payload.

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