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

With no annotations, the description carries the full behavioral burden. It discloses the 100-item cap and Australian scope, but says nothing about authentication requirements despite the access_token parameter, nor about error handling for invalid postcodes, rate limits, or what a resolved result contains.

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 short sentences, front-loaded with the operation and its scope. The unexplained "PRO" prefix is the only wasted token; otherwise the description is tight.

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 two-parameter read tool with no annotations and no output schema, the description is thin. It omits auth expectations, return shape (what a resolved postcode yields), and failure behavior, leaving the agent to guess at important call-time details.

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 50%: access_token is documented in the schema, while the required postcodes array is not. The description partially compensates by clarifying that the array holds Australian postcodes and is capped at 100, but gives no format details or validation rules.

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 and resource ("Resolve ... Australian postcodes") and adds batch scope with a 100-item cap. It distinguishes itself implicitly from the single-lookup sibling via "batch" and the limit, but never names postal_lookup or explains the distinction explicitly.

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 100-postcode cap implies this is the bulk path versus postal_lookup, but the description never states when to choose one over the other or when not to use this tool. Usage must be inferred from the word "batch" and the limit.

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