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

Annotations already declare readOnly/idempotent/non-destructive, and the description partly restates that ('Read-only, no side effects'). It earns credit for adding substantive behavioral context beyond annotations: the return format (text summary plus structured JSON) and the interpretation traps around parental_leave_paid_pct, one-way avg_commute_minutes, and raw pre-subsidy childcare rates.

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 purpose, then usage, then interpretation caveats, then return format. It is long and dense, but nearly every sentence prevents a concrete wrong answer, so little is wasted; the block of caveats could still be tightened.

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 return-value documentation is not required, yet the description still supplies the semantic caveats needed to interpret key fields correctly and fully covers when to use it versus siblings. Nothing an agent needs to call it correctly is missing.

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% and there is a single parameter, so the schema already documents 'city' as a slug with list_cities discovery. The description adds no syntax or format guidance for the parameter itself, so the baseline 3 applies.

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?

Names a specific verb+resource ('Concise profile of one city') and enumerates the exact contents returned: currency, tax shape, headline costs, safety-net values, freshness. It also explicitly distinguishes itself from a sibling ('Lighter than compare_cities'), so an agent can route without opening either 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?

States the selecting condition ('use when the user is asking about one place rather than a comparison') and names the alternative. It goes further by redirecting to compare_cities when childcare_income_tested or child_benefits_income_tested is present, which is an explicit when-not-this-tool rule.

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