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

Annotations already declare readOnly, idempotent, non-destructive behavior, so the bar is lower; the description still adds that it returns data plus source/freshness metadata and that its purpose is disclosing missing capabilities. That is meaningful behavioral context beyond the annotations, though no detail on output shape or pagination.

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 core purpose and usage cue are front-loaded and efficient, but the trailing 'Units: ft, kt, s, F, mi; directions FROM' block reads as copy-pasted boilerplate for a no-parameter coverage tool and does not obviously earn its place.

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 zero parameters and no output schema, the description adequately covers what the tool explains and that it returns source/freshness metadata. It could say more about how to interpret the coverage gaps, but nothing critical for calling it correctly is missing.

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?

The tool takes zero parameters, so the schema carries no semantic burden and the baseline of 4 applies. The description's units line is not tied to any input, which is harmless here.

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 (Explain) and resource (California API/MCP beta coverage, sources, missing capabilities), so an agent can tell it is a meta/coverage tool rather than a data fetcher. However, it does not differentiate itself from the sibling get_data_coverage, leaving overlap ambiguous.

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?

Gives a concrete when-to-use cue ('Check before claiming Florida parity, continuous advisories or break-level surf scores') that tells the agent to consult this before asserting parity or certain score types. It stops short of naming the alternative coverage tool (get_data_coverage) as a when-not/differentiator.

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