Tide times

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

Annotations already declare read-only, idempotent, open-world, and non-destructive behavior. The description adds important context: approximate accuracy (+/- 20 min), worldwide free availability, and that it returns empty for lakes. This goes beyond structured data, though it doesn't mention rate limits or exact return format.

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?

Four compact sentences front-load the core purpose, then caveats. Every sentence earns its place: model source, accuracy, constraints, and edge case. No redundancy or fluff.

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 adequately covers what is returned (times and heights relative to MSL). It notes limitations and edge cases. Missing information about required vs. optional parameters (none required) and whether lat/lon or spot_id alone suffices, but this is minor given the schema's clarity on types and defaults.

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 low (20%), with only spot_id annotated. The description does not explain lat/lon, days, or start_date semantics beyond what is implied. However, the schema itself provides types, ranges, and defaults for these parameters, so the baseline is 3. The description could clarify the interaction between spot_id and coordinates, which it only hints at via the schema note.

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?

States a specific resource (tide high/low water times and heights) with a named data source (Open-Meteo marine model) and a clear scope (coastal spots). Distinguishes itself from siblings like spot_forecast by focusing on tidal data rather than general weather or spot info.

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?

Clearly indicates when to use (for tide times at a coastal spot) and implicit exclusions via 'not for navigation' and 'Empty for lakes'. No explicit alternative tool mentioned, but the niche is well-defined. Could name spot_forecast as a broader alternative for weather.

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