auspost_get_postcode

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds nothing behavioral beyond that: it doesn't say whether a postcode query returns suburb lists, whether matches are fuzzy, whether it requires an AusPost API key, or anything about rate limits or error cases.

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?

A single front-loaded sentence with no filler. It is efficient, though the terseness borders on under-specification rather than economy.

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?

With no output schema, no sibling differentiation, an undocumented auth parameter, and no description of what a successful response contains (single postcode, list of suburbs, coordinates), an agent cannot confidently predict behavior. Given the density of nearby postcode/zip siblings, this is a significant gap.

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 only 50%: 'q' is documented as 'Suburb name or postcode', but api_key is undocumented in both schema and description. The description itself adds no parameter meaning (e.g., whether q accepts partial suburb names or must be a full 4-digit postcode), so it fails to compensate for the coverage gap.

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 and resource ('look up an Australian postcode or suburb'), so the agent knows exactly what domain it queries. It does not, however, distinguish itself from sibling tools such as postcode_lookup, postcode_random, zip_lookup or zip_by_city, which occupy closely overlapping territory.

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?

There is no guidance on when to use this versus postcode_lookup, zip_lookup, or zip_by_city, all of which appear in the sibling list. The agent must infer routing from names alone.

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