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

Annotations already declare the write/non-destructive/non-idempotent/open-world profile, and the description adds two pieces of value beyond them: the return value ('Returns the new list id') despite there being no output schema, and the underlying endpoint. It stops short of noting that duplicate list names are not deduplicated, which the non-idempotent hint implies matters.

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 short clauses, front-loaded with the operation class ('WRITE:') and the core action, then the return value, then the endpoint. No filler and nothing that could be trimmed without losing information.

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 two-parameter create tool with annotations covering the safety profile, the description supplies the essential missing piece—the returned id—so the agent can chain into get_list or import_contacts. It omits error behavior and whether the name must be unique, which are minor for this complexity level.

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% with clear min/max length constraints on both fields, so the schema carries parameter semantics fully. The description adds no extra meaning (e.g., uniqueness or naming conventions) beyond that, which is the baseline-3 case.

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 new, empty contact list') plus the transport endpoint (POST /lists). The 'empty' qualifier distinguishes it from import_contacts and the sibling create_* tools, so an agent can pick it without opening schemas.

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 'WRITE:' prefix and 'new, empty' wording imply this is for provisioning a container before adding contacts, but it never names an alternative (e.g., use emailchef_import_contacts to populate it, or emailchef_list_lists to check for an existing list first). Usage is implied rather than stated.

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