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

Annotations already indicate read-only, idempotent, and non-destructive behavior. The description adds beyond this: it explains that the tool returns the zone's segment from the latest bulletin plus the office-wide synopsis, includes Small Craft Advisories, and works only for coastal US waters. No contradictions.

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 concise at six sentences, each serving a purpose: stating the action, scope, return content, and explicit alternatives. No filler or repetition, information is efficiently front-loaded.

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?

Given the tool's complexity (mapping point to marine zone, returning narrative), the description covers key aspects: what is returned, geographic limitation, and alternatives. Lacks explicit mention of error cases or prerequisites, but overall it provides sufficient context for correct invocation without an output schema.

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% with clear parameter descriptions. The description adds value by explaining how the provided lat/lon maps to a marine zone and what the response contains (day-part wind/seas text, Small Craft Advisories). This contextualizes parameters beyond the schema, particularly the response_format purpose.

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 the tool retrieves the official NWS Coastal Waters Forecast narrative for a given point. It specifies the resource (CWF), verb (get), and includes sample output. It distinguishes from siblings by naming nws_get_wind_forecast and noaa_get_meteorological_data as alternatives, making the purpose unambiguous.

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 provides explicit guidance on when to use this tool (for narrative marine forecast) and when not to (for numeric wind or observed wind), naming specific alternatives. It also notes geographic constraints (point must be in US coastal waters, zone extends 20-60 NM offshore), offering clear context for appropriate use.

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