Validate postal addresses

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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds valuable behavioral context: the source (Google's address data), the validation criteria, the formatting behavior, and the fallback action when street/city are absent. This goes beyond the annotations without contradicting them.

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 with no redundancy. The main function is front-loaded, and the conditional behavior is stated succinctly at the end. Every clause earns its place, keeping the description lean yet informative.

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 complexity of an array of address objects and the existence of an output schema, the description covers the core purpose, key behavioral rules, and a conditional branch. Annotations cover safety and idempotency, so the agent has enough to decide invocation. Minor gaps like explicit error handling or output format details are complemented by the output 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 description coverage is 0%, so the description must compensate. It mentions required fields, postcode pattern, state/province, and street/city, providing context for those properties. However, it does not explicitly explain all parameters (e.g., 'name', 'organization'), and some properties like 'region' and 'country' have schema descriptions while others don't. The description adds partial value but leaves field-level semantics incomplete.

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 it checks addresses against country rules, validating required fields, postcode pattern, and state/province, and formats them. It distinguishes from sibling tools (check_emails, check_phones) by explicitly targeting postal addresses. The verb 'checks' and resource 'addresses' make the purpose unambiguous.

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 the domain (address validation vs email/phone), but the description does not explicitly reference alternatives or exclusionary conditions. It does provide a conditional hint ('Without street and city, returns...'), which aids usage but stops short of naming when not to use this tool. No explicit differentiation from siblings.

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