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

Even though annotations already declare read-only, idempotent, and non-destructive behavior, the description adds valuable context: it explains that differences are methodological (never an error), that the result specifies which definition each value carries, and that down sources report errors in place without sinking the comparison. These are meaningful behavioral details beyond the annotations.

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 four sentences long, front-loaded with the main action, and every sentence adds value: it covers purpose, usage, behavioral notes, and error handling. There is no fluff or repetition.

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?

Despite lacking an output schema, the description comprehensively explains what the tool returns (values side by side, citations, spread, definition labels) and how it handles source outages. It provides enough context for an agent to select and use the tool correctly, even in a complex multi-source comparison scenario.

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%, so the parameters are already well documented. The description adds some context by clarifying the tool fetches 'one indicator for one country' and iterates over all sources, but it does not significantly enhance the parameter semantics beyond what the schema provides. Baseline 3 is appropriate.

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 a specific verb ('Fetch') and clearly defines the resource: one indicator for one country across EVERY official source, showing values side by side with citations and spread. This distinguishes it from siblings like get_indicator (which likely returns a single value) and verify_stat (which checks claims).

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 the tool: 'Use when sources disagree, when you need to know WHICH official number to cite, or to check how large the methodological gap is.' It gives clear context but does not name alternative tools or provide explicit when-not-to-use guidance, so it falls short of a perfect 5.

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