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

With no annotations, the description carries the full burden. It usefully discloses that the lookup is free, limited to Australia, and returns locality, state and coordinates, but says nothing about invalid/missing postcode behavior, rate limits, or response structure.

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?

One compact sentence with the key scope and return values front-loaded; 'FREE' is brief and relevant to tool selection. There is 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 one-parameter lookup with no output schema, the description names the return fields and geographic scope, which is close to sufficient. It could be stronger by stating what happens for an unknown postcode, but nothing essential for a successful call is missing.

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 0% and the single parameter is undocumented in the schema, so the description must compensate. It adds that the postcode is Australian, which narrows valid input, but gives no format expectations (e.g. four digits) or error semantics.

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?

States a specific verb ('Resolve') and resource ('Australian postcode') and names the outputs (locality, state, lat/lon), so the agent knows exactly what the tool does. It does not distinguish itself from the sibling batch_postal, leaving the single-vs-batch distinction implicit.

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?

No guidance on when to use this instead of batch_postal or distance; the single-lookup scope is only implied. The agent must infer that batch_postal is for multiple postcodes and distance is for measuring separation.

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