create_or_update_user

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

With no annotations, the description carries the burden of disclosing side effects. It openly labels the operation as WRITE, notes idempotency, and states the deduplication rule ('cannot create duplicates'). It does not specify whether update replaces all fields or only provided ones, which is a notable gap, but the core behavioral traits are well covered.

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 long, front-loaded with the WRITE label and action, and every phrase adds value. It efficiently conveys purpose, matching criteria, endpoint, and idempotency without redundancy.

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 output schema exists and the tool handles a common upsert pattern, the description covers the essential purpose, matching keys, and safety properties. It falls short only in not clarifying update semantics for omitted fields, which is a meaningful but not fatal omission 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 only 17%, so the description must compensate. It adds meaning by identifying email and external_id as matching keys, and it implies the upsert logic. However, it does not explain the roles of name, role, phone, or organization_id beyond their obvious names, leaving several parameters under-documented.

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 clearly states the tool's verb and resource: 'Create a user, or update it if one already exists' with a specific endpoint. It distinguishes itself from siblings like get_user and search_users by describing upsert semantics and matching keys (email or external_id).

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 context is clear: use this tool to create or update a user based on email or external_id, and the idempotency guarantee is stated. However, it does not explicitly mention when not to use it or provide named alternatives, though the sibling list makes the distinction implicit.

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