Create a contact

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

The description discloses a non-obvious behavioral trait: existing contacts are not deduplicated. This goes beyond the annotations, which only indicate that the operation is not read-only and not idempotent. The warning adds practical value for agents deciding whether to call this tool repeatedly or to search first.

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?

The description is two sentences with no filler. It front-loads the core action, states the key requirement, and adds a valuable warning. Every sentence 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?

Given the tool's moderate complexity, the description covers the essential operational facts: what it creates, what is required, and the deduplication behavior. It is aided by the output schema and annotations, so it does not need to explain return values or safety semantics. A slightly fuller description of optional field relationships would make it complete, but it is not a significant gap.

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 schema description coverage is low (29%), but the description adds the important constraint that email or phoneNumber is required, which is not reflected in the schema's required array. Other parameters like firstName, lastName, and accountOwnerId are not explained in the description, though their names are reasonably self-explanatory. The description partially compensates for the schema gaps but not completely.

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 uses a specific verb and resource: 'Create a CRM contact.' It clearly identifies the operation and the domain object, distinguishing it from read, update, delete, and bulk-creation operations in the sibling list. However, it does not explicitly contrast itself with bulk_create_contacts, so the distinction is implicit rather than spelled out.

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 description provides clear usage context by stating that either email or phoneNumber is required, and by warning that existing contacts are not deduplicated. This helps an agent know what to provide and what to expect. It does not explicitly name alternatives like bulk_create_contacts or update_contact, but the guidance it gives is actionable and relevant.

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