create_contact

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

Annotations are empty, so the description carries the full burden. It does disclose one meaningful behavior beyond the schema: a 409 failure when the email already exists. It omits other mutation-relevant traits such as required scopes/permissions, whether creation triggers automations or welcome sends, and whether segment/topic assignment has side effects.

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 sentences, zero filler, with the core create action front-loaded and the failure mode appended as a compact caveat. Every clause earns its place.

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 7-parameter mutation tool with nested objects (topics, segments), no annotations, and no output schema, the description is adequate but thin: it explains what is created and one error case, but says nothing about the response, permission requirements, or the semantics of nested subscription choices.

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 71%, so the schema already documents most parameters (email uniqueness, custom properties, global unsubscribe). The description restates the segments and topics concepts but adds no format, constraint, or default information beyond what the schema provides; first_name/last_name remain undocumented.

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?

Specific verb ('Create') plus resource ('a contact') plus scope ('in the team audience'), with the two optional behaviors (segments, topic subscriptions) named. An agent can distinguish it immediately from siblings like update_contact, get_contact, and delete_contact.

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?

Usage is implied by 'Create a contact', and the 409-on-duplicate-email note usefully signals that an existing address must be handled differently, hinting at update_contact. However, it never explicitly states when to prefer this over update_contact or what prerequisite state (e.g., an existing audience/domain) is required.

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