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

Annotations already flag write, openWorld, and non-idempotent, but the description adds real substance: what ACTIVE means downstream (campaigns and automations), the return payload (contact id and status), and the underlying endpoint. It still omits duplicate-email behavior, which matters for a non-idempotent create.

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 sentences, front-loaded with a 'WRITE:' marker so the operation type is impossible to miss. Every sentence carries distinct information—payload, precondition, return value.

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 helpfully names the return values, and the nested custom_fields schema points to emailchef_list_custom_fields. But for a non-idempotent create it never addresses duplicate handling or failure modes, leaving a gap an agent would want covered.

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?

The description names email, name, and custom fields, and the schema documents status and custom_fields in detail (50% coverage overall). It adds little beyond the schema for list_id or the status enum values, so the schema still carries most of the load.

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 ('add a contact ... to a list') and enumerates the payload fields (email, name, custom fields). It does not explicitly distinguish itself from siblings like emailchef_import_contacts or emailchef_update_contact, so the agent must infer that this is the single-contact create path.

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?

'Only add people who agreed to receive email' gives a consent precondition, which is useful guidance. However, there is no explicit routing to alternatives such as bulk import or update for existing contacts, nor what to do when the email already exists.

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