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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description adds the behavior that matters here: the call is asynchronous, returns immediately with a job id, and requires a BYO personal access token. It does not discuss rate limits or what happens if the same request is submitted twice (though idempotentHint claims it is safe), leaving a small gap.

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?

Three sentences, front-loaded with the action, then prerequisites, then the follow-up protocol. Every sentence carries information the agent needs; nothing is redundant.

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?

There is no output schema, but the description compensates by stating what is returned (job id and status) and how to consume it downstream. Combined with the schema's example, an agent has everything needed to call it correctly.

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 coverage is 100%, so the schema already explains collection_id, inputs and _apiKey thoroughly. The description only reinforces that _apiKey is the user's own free token and that inputs must match the collection form, adding little beyond the structured fields; baseline 3 applies.

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 ('Submit a data-retrieval job to the Copernicus Climate Data Store') and immediately names its role in a three-step pipeline. It is clearly distinguishable from cds_collection (discovery), cds_job_status (polling) and cds_job_result (download link).

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?

Explicitly says to call cds_collection first to learn accepted inputs, and gives the full follow-up sequence: poll with cds_job_status until 'successful', then fetch the link with cds_job_result. Each alternative is named with the condition that selects it.

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