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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the safety profile is covered by structured data. The description contributes the return contract (a slug) and its consumers, but says nothing about no-match behavior, partial matches, or whether multiple candidates can come back for an ambiguous name such as a street that exists in several towns.

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 sentences, both earning their place: the first defines scope and output, the second defines downstream consumption. The most important information, what the tool returns, is front-loaded rather than buried.

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, the description carries the return-value burden and discharges it by naming the slug as the output. What remains missing is resolution behavior for ambiguous or failed lookups, which matters for a resolver that can match many entity types across a whole country.

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 documented in-schema, including examples for query and the enum/default for language. The description adds no formatting rules, postcode syntax, or address-ordering conventions beyond what the schema already states, so this lands at the baseline.

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 uses a specific verb ('Look up') and enumerates the resource types it resolves (municipality, town, district, neighbourhood, postcode, street, address), then states the concrete payload: a Huisly slug. That is enough for an agent to distinguish it from siblings like search_listings or get_place_insights 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?

It explicitly routes the agent forward: the returned slug feeds search_listings (location), get_place_insights (type and slug), or get_property (property_slug) for addresses. It stops short of stating when NOT to call it (e.g. when a slug is already known) or what to do when the query is ambiguous, but the downstream mapping is genuinely actionable.

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