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

Annotations only cover safety/idempotency flags; the description adds genuinely new behavior — the job runs in the background, returns upload_id and contact_count, and validate_emails consumes credits with a default of off. It omits what happens on duplicate or invalid rows, which is the main remaining gap for a non-idempotent bulk write.

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 dense sentences, front-loaded with the operation and its 50,000 cap; the credit cost of validate_emails and the return values are packed in without filler. Nothing reads as padding.

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?

With no output schema, the description usefully declares the return shape (upload_id, contact_count) and the async nature, so an agent knows not to expect synchronous results. It lacks error/duplicate handling guidance and a way to poll status, which keeps it just under complete.

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 baseline is 3, but the description adds a real constraint not encoded in the schema: 'Each contact needs email or linkedin_url' (item-level required is absent) and that unknown keys go in custom. That is meaningful semantics beyond the field descriptions.

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+resource+scope: 'Queue up to 50,000 contacts for import into a campaign.' No sibling tool in the set performs contact import, and the description makes the operation and its bounds unmistakable without opening the 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 clear context for invocation: contacts belong to a campaign, each row needs email or linkedin_url, and validate_emails is an opt-in that costs credits. It does not name a 'when not to use' case or an alternative path (e.g., single-contact creation), so it stops short of a 5.

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