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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, but the description adds critical behavioral context beyond that: how to handle parental leave data (quoting the summary field instead of relying on percentages) and how to interpret avg_commute_minutes (one-way, door-to-door, excluding WFH). The description also explicitly denies side effects ('no side effects'), reinforcing the annotations without contradicting them.

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?

The description is a single paragraph of moderate length and front-loads the key purpose. Each sentence adds necessary context, but the length could be slightly trimmed without loss. Still, it is efficient given the behavioral nuances it must convey.

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 an output schema present and only one parameter, the description fully covers the tool's purpose, when to use it, key behavioral quirks, and guidance for agent response generation. No gap is evident given the tool's simplicity.

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 100% for the single parameter, so the baseline is 3. However, the description adds value by implying the need for a city slug validated via list_cities, which helps the agent avoid invalid inputs. It does not repeat the schema type or length constraints, earning a 4.

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 specific verbs ('profile of', 'lighter than') and explicitly names the resource ('one city'), clearly distinguishing itself from sibling tools like compare_cities. It lists the exact data categories (currency, tax shape, costs, safety-net) so the agent knows precisely what to expect.

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 description explicitly states when to use this tool ('when the user is asking about one place rather than a comparison') and provides a direct alternative ('Lighter than compare_cities'). This clearly guides the agent away from using it for comparisons, with no ambiguity.

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