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

The annotations already declare this as a read-only, idempotent, closed-world tool, so the bar is lower. The description adds genuinely useful context that annotations can't express: results are two-mode (cities with counts vs. suburbs for a given city) and the returned names are valid inputs to another tool. It doesn't mention that unknown city values return nothing, which would be a small but helpful addition.

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?

Three sentences with zero filler, and the usage trigger is front-loaded ahead of the behavioral detail. Each sentence contributes distinct 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?

An output schema exists, so the description doesn't need to explain return values, and annotations cover the safety profile. What remains — the trigger condition, the two listing modes, and the cross-tool contract with search_migration_agencies — is fully covered.

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 100% and both parameters are already documented, including the city/suburb mode switch and the state enum. The description reinforces the mode switch ('with city set, the suburbs of that city') but adds no format or constraint details beyond the schema. Baseline 3 applies when the schema carries the 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 and resource: lists Australian cities with agency counts, or suburbs when a city is supplied. It also distinguishes itself from search_migration_agencies by describing the contrast between enumeration and lookup, so an agent can tell the two apart without opening a schema.

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 first sentence gives an explicit trigger condition ('when a location search finds nothing or the place is ambiguous'), and the last sentence names the follow-up tool and how to use its output. Nothing about when to choose this over its siblings is left to inference.

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