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

Annotations declare destructiveHint=true and idempotentHint=false, but the description adds the crucial two-phase confirmation semantics that the annotations cannot convey — that the first call is non-committing and only the second call with confirmation_token writes. It does not explicitly describe side effects on the target list (e.g. dedupe, overwrite), 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?

Front-loaded with purpose, then the phase flow, then parameter conditions, then post-commit guidance. Every sentence carries actionable content with no filler.

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 complex stateful, destructive, two-phase import with no output schema, the description covers the flow, commit semantics, parameter conditions, and follow-up. It stops short of describing the phase-1 preview contents and error/failure behavior, but it is otherwise self-sufficient.

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 conditional semantics the schema does not: provider_ids omitted means import all, list_id targets an existing list while list_name creates a new one, and confirmation_token is phase-2 only. This meaningfully enriches the parameters beyond the schema text.

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 (import) plus resource (lead rows) and origin (a prior search_external_leads session) into a lead list. This clearly distinguishes it from siblings like search_external_leads (which produces the session), create_list, and find_leads.

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?

The two-phase flow (phase-1 preview + token, phase-2 commit with confirmation_token) is spelled out, as is when to use list_id vs list_name and what omitting provider_ids does. It even gives forward guidance to reuse the returned list_id for campaign creation. The only gap is an explicit 'don't use this if...' exclusion.

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