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

Annotations already declare readOnly, idempotent, openWorld, non-destructive, so safety is covered. The description adds substantive behavior: the source dataset, coverage window, ordering (newest first), and the exact fields returned including cause codes and casualty/damage fields — useful context beyond what annotations provide.

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 purpose and coverage are front-loaded, followed by return fields, ordering, filters and examples. It is a long sentence but each clause (dataset, fields, ordering, filters, use cases) carries information; minor redundancy in the cause-code examples.

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?

With no output schema, the description does well to enumerate returned fields and default ordering, and all seven optional parameters are documented. It stops short of explaining whether filters combine with AND logic or how to page beyond the limit parameter, but nothing critical is missing for correct invocation.

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%, and the schema already documents every parameter including the cause-code prefix semantics and accident-type substrings. The description largely restates those filters and example values without adding new syntax or combination rules, 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 (US train accidents/derailments from FRA Form 54, 1975–present) and specifies it returns individual reports rather than aggregates, which implicitly separates it from rail_accident_summary. It never names that sibling explicitly, so it falls short of full sibling differentiation.

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 gives clear usage context with concrete example queries ('train derailments in Ohio in 2023', 'Norfolk Southern accidents') and lists the available filter dimensions with a sensible ordering guarantee (newest first). It does not state when to prefer rail_accident_summary or note exclusions, so no explicit when-not guidance.

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