create_mailing_list

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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so the safety profile is covered. The description adds only the return-ID fact; it does not state the meaningful consequence of idempotentHint=false (repeated calls with the same name create duplicate lists) or any naming/uniqueness or permission constraints. Useful but thin beyond what structured fields already give.

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?

Two short sentences, front-loaded with the create action and the returned ID. The second sentence about list visibility and opt-in is largely redundant with the schema and slightly dilutes the focus, but nothing is padded excessively.

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 correctly tells the agent the call returns an ID, and all five parameters are fully covered by the schema. The main gap is behavioral: nothing about duplicate-name handling or whether the new list is immediately usable in campaigns, which would matter for a non-idempotent create.

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 description coverage is 100%, so all five parameters — including the public/private and single/double opt-in semantics — are already fully documented in the schema with the same parenthetical explanations. The description's second sentence merely restates that schema content, adding no new meaning, 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?

States a specific verb and resource ('Create a mailing list') plus what it returns ('its ID'), which immediately separates it from get_mailing_lists, update_mailing_list and delete_mailing_list. It even names the downstream consumers of the returned ID, so an agent knows this is the entry point of the list lifecycle.

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 reference to 'other tools use to subscribe people and target campaigns' implies this is a prerequisite step before add_subscriber or create_campaign, but it never states when to create versus reuse an existing list, nor any prerequisites or exclusions. Usage is implied rather than prescribed.

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