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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds context annotations cannot: the 2000-address cap, the degraded behavior for larger jobs, and that the call is free of credit cost. It omits what happens if the job isn't complete (error vs. partial), but the behavioral picture is otherwise solid.

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 resource and scope, then the size cutoff, then the downstream instruction, with no filler. "Free." is a fragment but it carries real decision-relevant information.

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, so the description must carry the return semantics; it does state that the payload is a CSV meant to be surfaced as a file. It remains unclear whether the tool returns a string, a URL, or an attachment object, and what happens for an unfinished job.

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?

With one parameter at 100% schema description coverage, the schema already explains list_id and its provenance from create_bulk_job. The description adds no further meaning about the parameter, so the 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?

The description names a specific resource (the complete results CSV of a completed bulk job) and a verb-like action ("get" / "hand it to the user as a .csv file"), which is more than a restatement of the title. It implicitly contrasts with get_bulk_summary by stressing "complete results file," but no sibling is named explicitly, so it falls short of full differentiation.

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?

"For jobs of up to 2000 addresses" plus "Larger jobs only get download_url" gives an explicit use condition and an explicit non-use condition with the alternative mechanism. It does not say to confirm job completion via get_bulk_status first, which is a meaningful precondition left implied by "completed bulk job."

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