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

Annotations already declare read-only, idempotent, non-destructive. The description adds meaningful behavioral context: events are deterministic rule-based detections, thresholds are disclosed in each record, nothing is model-generated, and missing index yields a specific error format. This goes well beyond the annotations.

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?

Four dense sentences with zero filler. The first sentence states purpose, the second provides usage guidance, the third explains data provenance, and the fourth covers filters and return format. Every sentence adds value and is well-organized.

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 no output schema, the description specifies the return shape ({count, events, filters}) and the error case. It covers all parameters, the underlying data source, and filters. For a list tool with this complexity, the description is complete and leaves no significant gaps.

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 has 0% description coverage and no enums, so the description carries the full burden. It clearly explains each filter: status with examples, country as EU-27 ISO2 (Greece = 'EL'), domain with examples, and min_severity with an explicitly ordered scale (info < watch < warning < severe). This is exactly the missing parameter semantics.

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 opens with a specific verb+resource+scope: 'List detected travel-disruption events for EU-27 tourism.' It clearly distinguishes from siblings by positioning this as the browse/filter tool and explicitly directing trip-specific questions to assess_trip.

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?

Explicit usage guidance: use for browsing/filtering across countries, and 'for a question about one specific trip, use assess_trip.' This directly tells the agent when to prefer an alternative, satisfying the when-to-use and when-not-to-use criteria.

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