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

Annotations cover the safety profile (readOnly=false, destructive=false, openWorld=false), so the bar is lower; the description adds real value by disclosing a data-provenance constraint on which contacts may enter the list and by describing the returned fields array. It stops short of noting failure modes or whether the call is idempotent.

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 sentences, purpose first, then the policy constraint, then response shape. The long provenance clause is dense but every sentence carries information an agent would otherwise lack.

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 annotations, full schema coverage and an output schema, the description only needs to supply policy and return-shape context, which it does via the consent-source rule and the fields array note. Minor gaps like workspace defaulting behavior are already 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 description coverage is 100%, so all seven parameters are already documented in the schema, and the description adds nothing about them. The mention of the response `fields` array is return-value context, not parameter meaning, so 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 opens with a specific verb and resource: 'Create a new contact list,' which is distinct from sibling create_folder and from read siblings get_list/get_all_lists. It doesn't explicitly name an alternative, but the resource is unambiguous enough that an agent can route correctly.

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 gives a substantive rule about acceptable contact provenance ('evidenced import or consent source'), which is implied usage guidance, but it never states when to reach for create_list rather than create_folder or create_workspace, nor any prerequisites like permissions or workspace scoping.

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