Light definition

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

With readOnly/idempotent hints already covering the safety profile, the description adds real context: the data is a pre-release 0.x package whose content is still being checked, entries and paragraph cites are verbatim, and the tool surface is a 0.0.x preview subject to change. It does not state what happens on an unknown id, but the provenance and stability disclosure is well 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 core definition is front-loaded and the coverage limits are useful, but the text repeats itself: verbatim is asserted twice and the pre-release/0.x caveat appears in two separate places. Tightening would remove redundancy without losing any constraint.

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 single-parameter read-only lookup with no output schema, the description supplies the return shape, the id format, and the data-coverage boundaries, which is close to sufficient. The main gap is error behavior for an invalid or unknown light id, which the agent cannot infer from either the schema or the annotations.

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%, so the baseline is 3, but the description adds two facts the schema lacks: the "light:" prefix is optional, and arcs follow the bearing convention returned alongside the id. Those directly affect how the agent constructs and interprets the single required parameter.

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?

Opens with a concrete verb+resource: returns the definition of one light from colregs data, and enumerates exactly which fields come back (name, Rule 21 paragraph, colour, character, arc, placement). It partly separates itself from siblings by scoping out Part B steering rules and saying it is not for navigation, though it never names rule_text or evaluate directly.

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 negative scope ("Not for navigation", no day shapes, no sound signals, no Part B steering rules) implies that rule_text or evaluate cover those cases, and the id example hints that evaluate consumes these ids. But there is no explicit statement of when to call this versus the two siblings, so the agent must infer the routing.

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