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

Adds substantial context beyond the readOnly/idempotent annotations: it discloses the confidence taxonomy (confirmed, reported, estimate, billed in USD), the source attribution, the last-read date, and the ECB-rate conversion applied only to confirmed markets. That is exactly the behavioral detail an agent needs to interpret results.

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 trigger sentence, then a compact enumeration of return content. The second sentence is long and parenthetical-heavy, but each clause carries distinct information; trimming would lose meaning.

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?

For a one-parameter lookup with an output schema and full annotation coverage, this is complete: the agent knows when to call it, what source backs the figure, how reliable the number is, and what conversions accompany it.

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 the single country parameter already documents accepted forms (name, ISO code, alias with examples). The description adds nothing parameter-specific, which is acceptable but earns only 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?

States a specific verb and resource — what GTA 6 costs in a given country — and names the two data sources. An agent can distinguish it from siblings like get_launch_countdown or get_facts without opening any 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?

"Use this when someone asks what GTA 6 costs in a country" gives an explicit trigger condition. It doesn't mention alternatives (e.g. list_markets for discovery, check_claim for verifying a quoted price), so routing is clear but not exhaustive.

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