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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description complements these by specifying the source (NASA GIBS) and the components returned (service URL, tile matrix set, image format), which adds useful context beyond the annotations. It does not contradict the annotations and provides clarity on the read-only nature of the operation.

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 a single paragraph that front-loads the primary action and purpose, then provides concrete examples and integration context. It's efficient with no filler, though slightly longer than strictly necessary. Every sentence contributes to understanding the tool's function and usage.

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 single parameter, full schema coverage, and presence of an output schema (so return values need not be described), the description is complete. It explains the tool's role in the EONET ecosystem, the source of the data, and the format of the response, which is sufficient for an agent to call it correctly. No critical information 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 input schema has 100% coverage for the single parameter category_id, listing all valid IDs explicitly. The description adds a cross-reference to eonet.events.categories for obtaining the ID, which is helpful, but the schema already fully documents the parameter. The description doesn't add meaning beyond the schema; it just reinforces the source. Baseline 3 is appropriate.

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 action (retrieve GIS web service layers), the resource (EONET event category), and the output (WMTS/WMS configurations from NASA GIBS). It distinguishes from sibling eonet tools like categories, list, and detail by focusing on layer retrieval, and even gives concrete examples of layers per event type. An agent can immediately understand the tool's purpose.

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 explicitly instructs to 'Pass a category ID from eonet.events.categories', establishing a clear prerequisite and pointing to the correct source for the parameter. It also explains the use case (visualizing satellite imagery) but doesn't explicitly state when not to use it or name alternatives. However, the dependency on categories is clearly stated, which provides strong usage guidance.

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