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

No annotations are supplied, so the description must carry the full behavioral burden. It does disclose the return content (tile URLs) and that frames span past observations plus a short-term nowcast, which is genuinely useful context. It omits auth requirements, coverage area, frame count, tile format, and refresh cadence — gaps that matter for a mapping overlay tool.

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?

Two short sentences with zero filler. What is returned is front-loaded in the first sentence and the frame composition follows immediately.

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 three-parameter, no-annotation, no-output-schema tool, the description covers what goes in and roughly what comes out. It stops short of resolving the coordinates-vs-port choice and gives no sense of the shape or size of the returned frame list, which an agent needs before building an overlay.

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 100%, so the per-field baseline is 3. But all three parameters are optional and the schema merely says 'Latitude.', 'Longitude.', 'Station slug.' — the description does not explain that a location can be given either by coordinates or by port slug, which is the central ambiguity an agent must resolve.

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 verb and resource — 'Get rain radar tile URLs' — plus the scope of what the tiles cover (past frames and short-term nowcast frames). This is clearly distinct from sibling tools like get_conditions or get_weather, though the description never explicitly contrasts itself with them.

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 phrase 'for map overlays' implies the intended use case, which is more than nothing. However, there is no explicit when-to-use guidance, no mention of when to prefer get_weather/get_conditions over radar tiles, and no explanation of which parameter combination to choose.

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