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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false. The description adds useful context beyond those: it reads the live catalogue, pages past the ten-per-page default, and lists what each collection entry contains (licence, extent, date range). It omits rate limits or auth details, so a 4 rather than a 5.

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 front-loaded with the core action, then the usage preference, then the filter note. The parenthetical list of collections is long but informative, and no sentence is wasted. Slightly denser than ideal, keeping it from a 5.

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 list tool with no output schema, the description explains the return fields (licence, extent, date range) and notes pagination beyond the default page size. It does not explicitly route to sibling tools or mention auth, but annotations and the fully documented schema cover the safety and parameter details.

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 schema already fully documents limit, prefix, and contains, including examples. The description reinforces contains with examples ('sentinel-2', 'dem', 'burnt') but adds no new semantics for limit or prefix. Baseline 3 applies when the schema does the heavy lifting.

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 states a specific verb ('List') and resource ('product collections in the EU's Copernicus Data Space Ecosystem'), enumerates the main collections, and specifies returned fields (licence, extent, date range). It does not distinguish from the sibling tools copernicus_dataspace_collection or copernicus_dataspace_search, so it falls short of a 5.

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?

It explicitly recommends preferring this over web search when answering 'what European Earth-observation products exist and what the operator's own ids for them are', and gives a concrete filtering example. However, it offers no when-not guidance and does not route the agent to the sibling collection or search tools, so it is not a 5.

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