Light definition

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

Beyond the readOnly/idempotent annotations, the description discloses that the content is verbatim from a pre-release data package, that nothing is paraphrased, that the surface is a 0.0.x preview subject to change, and that it is not for navigation. This is substantial behavioral context not available from annotations alone.

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 description is dense but front-loaded with the core purpose and output fields, followed by necessary caveats. A few caveats are repeated in spirit, but each sentence adds useful information for a tool with significant data-quality warnings.

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 return fields, mentions the bearing convention for arcs, specifies coverage and exclusions, and warns about data maturity. For a single-parameter read-only tool, this is complete enough for an agent to call it correctly.

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% for the single 'id' parameter, so the baseline is 3. The description adds meaningful context by explaining that ids come from evaluate_display, giving concrete examples, and noting that the 'light:' prefix is optional.

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 clearly states that the tool returns one light's definition from the colregs data package, listing the exact fields included. It is distinct from sibling tools because it ties ids to evaluate_display, but it does not explicitly name or contrast the other sibling tools.

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 gives explicit scope and exclusions: COLREGS Part C lights only, international text only, lights at night only, and no day shapes/sound signals/Part B rules. It also clarifies the id provenance via evaluate_display, helping an agent decide when this tool is appropriate.

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