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

Beyond the annotations (destructiveHint=true, idempotentHint=true), it discloses two things the annotations cannot: the cascading effect on the list's contacts and a 7-day post-creation restriction. The cascade phrasing ('removes the list's contacts from it') is slightly ambiguous about whether contacts themselves are deleted or merely detached, and irreversibility is only implied by the verb.

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?

Everything is packed into one dense sentence with no filler, and the core action plus the preview/confirm gate are front-loaded. It reads as a run-on, but no sentence is wasted.

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 destructive 3-parameter tool with no output schema, the description covers the safety workflow, the cascade effect, and the eligibility window. The only gap is the unmentioned dry_run flag, which is nonetheless fully documented in the schema.

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 list_id and confirm are already documented in the schema; the description's 'Needs list_id' and confirm: true restate that. The dry_run parameter is never mentioned in the description, so it adds no meaning beyond structured fields.

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 leads with a specific verb and resource ('Delete a contact list by ID'), which separates it from the many other delete_* siblings by naming the object type. It does not explicitly route away from alternatives like delete_segment or delete_contact, but the resource naming is specific enough to disambiguate.

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?

It spells out the intended call sequence: this shows a preview first and only deletes with confirm: true, plus an eligibility rule (only allowed 7 days after list creation). It gives no explicit 'when not to use' or alternative-tool guidance, but the workflow and constraint context is concrete.

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