check_comparability

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

No annotations are provided, so the description fully carries the behavioral burden. It clearly discloses that the tool is registry-backed only, hand-curated, does not compute correlations, and returns false as an expected outcome rather than a failure. This is strong transparency, though it doesn't mention side effects or auth needs (which appear irrelevant for a lookup).

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?

Three sentences with no wasted content: purpose, restrictions, and result interpretation are all present. The first sentence is a question rather than a declarative, and the parenthetical creates mild confusion, but overall it is efficient and front-loaded.

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?

The description gives all necessary preconditions for invocation and explains how to interpret a false result. Since an output schema exists, return-value details are not needed. It could mention what to do when comparable is true, but that is not essential for correct invocation.

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 0%, so the description must compensate. It adds that stat_keys must come from list_datasets for the same country and hints at country values ('ireland' or 'united-kingdom'). However, the parenthetical placement is ambiguous (it appears after 'stats', not country) and it never defines what a stat_key looks like. Partial compensation for the schema gap.

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 action (checks existence of a registered, hand-vetted comparison), names the resource (StatsMapped registry), and distinguishes itself from computing fresh correlations with 'never computes a fresh correlation'. This makes it distinct from siblings like list_comparisons or get_comparison.

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 explicit when-not-to-use guidance ('never computes a fresh correlation for an arbitrary pair') and a hard prerequisite: both stat_keys must come from list_datasets(country=...) for the SAME country. It also pre-empts misinterpretation by stating that a 'comparable: false' result is normal and should not be routed around as an error.

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