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

Beyond the readOnlyHint/idempotentHint annotations, the description discloses meaningful behavioral traits: the API is keyless and public-domain, lat/lon automatically selects the nearest station, results are high/low events over an inclusive date range, and times are in local station time with a configurable datum. No statement contradicts 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?

Three sentences, front-loaded with the core return type, then input modes, then output specifics and use cases. Every sentence earns its place and there is no redundant or filler content.

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?

Even without an output schema, the description explains what the agent will receive: times and heights of each high and low tide, inclusive date range, local station time, and datum. The only minor gap is not explicitly stating that at least one of station or lat/lon is required, despite the task having zero required parameters in the 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%, and the description adds valuable semantics not in the schema, such as the automatic nearest-station behavior from lat/lon, the default MLLW datum, and a concrete station id example for San Francisco. This goes beyond the schema's own field descriptions.

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 and resource: 'Return high and low tide predictions (times and heights)' from the NOAA CO-OPS API. It is clear and specific, though it does not explicitly differentiate this tool from the nearby sibling 'water_levels', so it stops short of full 5-level 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?

The description gives concrete use cases ('tide tables, beach and boating planning, or coastal scheduling') and clarifies the two input modes (station id or lat/lon). It does not explicitly state when not to use this tool or direct the agent to an alternative like water_levels, but the context is clear and actionable.

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