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

Annotations already establish the operation is read-only, idempotent, and non-destructive. The description adds useful behavioral context beyond those hints by disclosing that per-item errors are returned inline, which tells the agent that one invalid address will not necessarily fail the entire batch.

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 concise sentences with no filler. The first sentence leads with the action and scope, and the second adds the key error-handling behavior. Every phrase earns its place.

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 single-parameter tool with rich annotations and full schema coverage, the description is largely sufficient. It covers scope, batch limit, and inline error behavior. A minor gap is the lack of any statement about the success response shape, though no output schema exists to compensate for that.

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 100%, so the schema already documents the items parameter well. The description largely restates this ('up to 50 US addresses') rather than adding new parameter-level meaning, so the baseline of 3 is appropriate.

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 states a specific verb ('Validate'), a clear resource ('US addresses'), and a concrete scope ('up to 50... in one request'). This clearly distinguishes it from the single-item sibling address_validate and from enrichment-oriented siblings like address_enrich.

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 context: use this when validating multiple US addresses in a single call. It does not explicitly name alternatives or state when-not-to-use, but the batch scope and limit make the intended use obvious.

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