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

No annotations, so the description bears the full burden; it discloses the auth constraint (owner only), the visible effect (customer-facing contact on canceled invoice/quote links), and the null/omitted fallback to the owner's own email and phone. It stops short of stating reversibility or what happens to existing values, but covers the key behavioral traits.

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 tight sentences; the purpose is front-loaded and the fallback rule follows immediately. No wasted text.

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 simple 3-param tool with an output schema and no annotations, the description covers purpose, permission scope, and null semantics. Nothing critical is missing, though noting effects on existing values would have been a nice addition.

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 67%, and the description adds real meaning beyond the schema by explaining the omit-or-null fallback behavior for both email and phone. shop_id remains undescribed in the schema but is self-evident as the target shop.

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 'set' plus resource 'contact' described precisely as the phone and email customers see on a canceled invoice or quote link. This differentiates it from sibling settings tools (shops_setTips, shops_setInvoiceReminders, etc.), though it doesn't explicitly bound against them.

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?

'(owner only)' sets a permission-bound context for when it applies, but there is no explicit when-to-use/when-not guidance or named alternative. Usage is implied by the visible-on-canceled-link framing rather than spelled out.

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