upsert_customer

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

With no annotations, the description carries the burden and does so well for the risky part: it flags LEGACY, IMMEDIATE WRITE, HIGH RISK, and that it BYPASSES INFLOW_ENABLE_SAFE_WRITES. It does not describe return shape or the concurrency/timestamp behavior (timestamp param), but the risk profile is the critical disclosure here.

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?

Extremely tight: the critical warning is front-loaded in a bracketed banner, followed by the redirect and the one-line purpose. Every clause earns its place and nothing is wasted.

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 17-parameter mutation tool with nested objects and no output schema, the description supplies the essential safety context and the migration target. It omits return/mutation-status behavior, which is a minor gap given the fully documented schema.

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 100%, so all 17 parameters (including nested contacts/billingAddress/shippingAddress) are already documented in the schema. The description adds no parameter-level meaning beyond what the schema provides; baseline 3 applies.

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+resource combination ('Create a new customer or update an existing one') and explicitly names the preferred sibling tool (set_customer). The agent can distinguish this from upsert_product/set_customer without opening the schema. Slightly generic on the upsert semantics but fully clear.

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?

Explicitly routes the agent away: 'Use set_customer instead.' That is a concrete alternative for the common case. It does not state the narrow condition under which this legacy path is still appropriate (e.g., when INFLOW_ENABLE_SAFE_WRITES is off), leaving a small inference gap.

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