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

No annotations are provided, so the description carries the full burden. It discloses that all fields are optional and that a city alone is a valid record, which adds behavioral context. It also clarifies the one-of relationship between contactId and companyId. It doesn't mention response format or error handling, but for a create operation this is acceptable.

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 three short sentences with zero fluff. The action is front-loaded, and the two key constraints (one-of, optionality) follow directly. Every sentence earns its place; there is no redundant information.

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 create tool with 0 required parameters and no output schema, the description covers the essential behaviors: the action, the one-of constraint, and optionality. It doesn't discuss validation errors or return values, but these are less critical given the tool's simplicity. The schema already describes is_primary's demotion behavior, so the description doesn't need to repeat it.

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 60%, leaving city, country, companyId, and contactId undocumented. The description compensates by clarifying the exact-one-of rule for contactId/companyId and stating all fields are optional. This adds meaning beyond the schema for the critical parameters. The remaining fields are self-explanatory.

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 purpose: 'Add an address to a contact or company.' It uses a specific verb and resource, and distinguishes itself from sibling tools like addresses_update and addresses_delete by the action. The one-of constraint (contactId/companyId) is front-loaded, leaving no ambiguity.

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: to create an address for a contact or company. It explicitly states the rule to pass exactly one of contactId or companyId, which is a direct usage guideline. It doesn't compare to alternatives like addresses_update, but the purpose is self-evident from the name and the description.

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