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

Beyond the readOnly/idempotent annotations, it discloses the auth requirement (same _apiKey / Personal Access Token that submitted the job), the not-found behavior (found:false for unknown or other-account ids), and the meaning of the ready flag. These are exactly the operational facts an agent needs to poll correctly and to diagnose a false result.

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?

Front-loaded with the purpose, then status values, edge case, follow-up action, and auth in a compact block with no filler. Slight redundancy with the schema on _apiKey and the token-acquisition instructions keeps 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?

An output schema exists and annotations cover the safety profile, so the description need only add operational context — polling guidance, not-found semantics, and credential requirement — all of which are present. Nothing needed to invoke or interpret this tool 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?

Schema coverage is 100% and the schema already states job_id comes from cds_submit_request (job.jobID) and that _apiKey must be the submitting token, so the description largely restates schema content. The added 'same _apiKey' emphasis is minor value on top of the baseline.

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?

Specific verb+resource: 'Check a Copernicus Climate Data Store retrieval job'. It explicitly anchors to the sibling that created the job (cds_submit_request) and enumerates the status values, so an agent can distinguish it from cds_submit_request and cds_job_result without opening a schema.

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 an explicit control flow: 'Poll until ready is true, then call cds_job_result', naming the follow-up sibling and its trigger condition. It also implicitly excludes use as a submission tool by tying the input to a job created by cds_submit_request.

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