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

The description adds substantial behavior beyond annotations: it discloses Markdown formatting, stripping of client widgets, language fallback to English, and the betting-editorial exclusion. Since the annotations already mark it read-only/idempotent/non-destructive, this extra context gives a clear picture of what the call will return and transform.

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?

A single dense sentence communicates the resource, key fields, output format, localization behavior, and an important content exclusion with no filler. The betting-editorial note earns its place and does not bloat the definition.

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?

Despite having no output schema, the description enumerates the expected content fields and transformations, which is sufficient for most agents to understand the return shape. It does not detail error/not-found behavior or exact property names, but this is a low-complexity, two-parameter tool and the description is still quite 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 description coverage is 100%, with slug documented as coming from search_articles and locale fully enumerated. The tool description adds only general context ('by slug', language fallback) rather than parameter-specific meaning, so the schema carries the load 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?

States the exact resource ('One UFCalendar article') and retrieval key ('by slug'), then enumerates the returned fields and localization behavior. This is specific enough to distinguish from sibling search_articles, which is a search-oriented lookup.

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 description implies the tool is for fetching a single article once a slug is known, and the slug parameter's schema says it comes from search_articles. However, it never explicitly states when to choose this tool over alternatives, nor does it spell out when-not scenarios beyond the betting-editorial exclusion.

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