Create Contact

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

Annotations already declare readOnly=false, idempotent=false and destructive=false, so the safety profile is partly covered. The description adds genuinely new behavioral context: creating a contact can trigger the organization's active automations, which may send messages — a side effect an agent would not learn from the annotations or schema.

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 the core action and constraint, with no filler. Every sentence carries distinct information: purpose, identifier requirement, custom-field mechanics, side effect.

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 mutation tool with no output schema, the description covers the key preconditions (identifier requirement, custom-field keying) and the important side effect of automation triggering. It omits permission requirements and any indication of what the created contact record returns, which are minor given none exist.

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 71% and the schema lists zero required parameters, so the description's 'at least one of email/phone_number/external_id is required' fills a critical gap. It also explains that `properties` keys must match the field keys returned by list-contact-properties, adding meaning beyond the schema's generic 'Custom field values' note.

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 contact') and immediately adds scoping detail about identifiers and custom fields. It does not explicitly contrast with siblings like update-contact, but the create action is unambiguous against a family of get-*/update-* tools.

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 'at least one of email, phone_number or external_id is required' clause is a real usage constraint, and it routes the agent to list-contact-properties for custom field keys. However, it gives no guidance on when to choose create-contacts vs. update-contact or add-contacts-to-list, leaving alternatives to inference.

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