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

Annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false, openWorldHint=false), so the bar is lower. The description adds that comparisons are US-relative and span multiple datasets with a consensus ratio, plus a bidirectional salary equivalence, which is genuinely useful context beyond the structured fields, but it does not disclose anything about determinism, latency, or data freshness.

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?

A single dense sentence that front-loads the core action and then lists distinct outputs, with no filler. It is somewhat run-on, but every clause carries information an agent can use.

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?

Given a 2-parameter schema at full coverage, rich annotations, and an existing output schema, the description is largely complete; the output enumeration is arguably redundant but harmless. The only real gap is routing guidance versus the many compare_* siblings, which is not addressed.

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 the schema already explains both 'a' and 'b' as ISO 3166-1 alpha-2 codes with the differing requirement. The description adds no meaning beyond the schema, so the baseline of 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?

The description states a specific verb and resource (side-by-side comparison of two countries) and enumerates the concrete outputs: US-relative price levels across named datasets, consensus ratio, percent difference, and salary equivalence. It implicitly distinguishes itself from narrower siblings like compare_food_cost or compare_housing by being the comprehensive cost-of-living comparison, though it never names an alternative explicitly.

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?

There is no when-to-use or when-not-to-use guidance and no reference to any sibling tool. An agent must infer from the output enumeration that this is the broad cost-of-living comparison rather than a slice like compare_inflation or compare_total_cost. No prerequisites or exclusions are stated.

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