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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real behavioral value beyond that: alignment by period and an explicit failure mode (mixed frequencies fail with a message naming which keys differ). It does not describe pagination or how much history is returned by default, keeping it below 5.

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?

Two tight sentences with zero filler. The core behavior ('2-4 indicators aligned by period') comes first, followed by the usage example and the failure constraint in priority order.

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-shape explanation is unnecessary, and the schema covers the date format and key sourcing from list_macro_indicators. What remains thin is the default history window behavior and whether 'from' truncates all series identically — minor gaps for a read-only comparison tool.

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 50% (the array param itself has no top-level description), and the description compensates by imposing a semantic constraint the schema cannot express: all keys must share the same frequency. It also reinforces the 2-4 key bound, which matches minItems/maxItems, though 'from' is only documented in the schema.

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 concrete operation and scope: history of 2-4 indicators aligned by period, plus a representative question ('are wages growing faster than prices'). The multi-key framing implicitly separates it from the single-indicator sibling get_macro_indicator, but no sibling is named explicitly, so the differentiation is inferred rather than stated.

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 example question gives an unambiguous use context, and the same-frequency requirement tells the agent when the call will fail. It does not name a fallback (e.g., use get_macro_indicator for a single series) or say when-not to use it, so it stops short of a full routing rule.

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