Closest places by driving time

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

Annotations already carry the safety profile (readOnly, idempotent, non-destructive), and the description adds the non-obvious cost model — one route call per candidate — plus the exclusion rule that un-routable places are silently dropped, and the dependency on current traffic. These are behavioral facts an agent cannot infer from annotations or schema.

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?

Front-loaded with the action and ordering rule, then usage example, then mechanics, then alternatives — a natural decision order for an agent. Every sentence adds information; nothing restates the title or schema.

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 covers ordering (quickest first) and a key caveat (un-routable places omitted), which is enough to call it correctly. It stops short of saying what each ranked result contains (drive time value, place identifiers), a minor remaining gap for a tool whose response has no schema.

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%, so the baseline is 3; the description goes further by explaining that `candidates` are Balad's top places of that kind in the box as bl_nearby lists them, which links the parameter to a sibling tool's output. It says little extra about open_now or radius_km, but those are already well documented in the schema.

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: rank places of one kind around a point by driving time, quickest first, under current traffic. The scope (a search box of candidates, not all places) and the distinguishing trait versus bl_nearby (drive-time ranking rather than proximity listing) are both explicit.

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?

Gives a concrete trigger question ("which pharmacy / gas station / hospital can I reach fastest from here") and names two alternatives with the condition that selects each: bl_nearby for more places without drive times, bl_place for details of the winner. When-to-use and when-not-to-use are both covered.

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