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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds a useful behavioral trait beyond annotations: each returned value carries its own live listing count, telling the agent the response is enriched with popularity/count data rather than a plain enum list.

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?

Two sentences, front-loaded with the core purpose and response characteristic, then the parameter mapping. The enumerations are long but each item is load-bearing given nine facets; minimal waste.

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?

Output schema exists, so return structure needn't be explained. For a single-param facet-discovery tool, the description covers purpose, response enrichment, and the param-to-group mapping. Only minor omission is any note on caching/freshness of the 'live' counts.

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% (baseline 3), but the description goes further by mapping human-readable filter names (used_or_new, case_material) to the actual upstream group ids the parameter takes (usedOrNew, caseMaterial), which is exactly the camelCase form the schema documents. This disambiguation adds real value beyond the schema text.

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+resource: the discovery endpoint returning all accepted values for each of chrono24_search's filter params, and it names the exact facet groups covered. An agent can distinguish it from chrono24_search and other chrono24_* siblings (brands, models, autocomplete) 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 ties the tool to chrono24_search's advanced-search filter params, implicitly establishing when to call it (to discover valid filter values before searching). It does not state explicit exclusions or a step-by-step 'call this before search' instruction, so it stops short of 5.

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