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

Annotations already declare read-only, idempotent, non-destructive, closed-world, so the description is free to add genuinely new behavior: a 1500-value per-call cap, differing results by account tier, truncation signalled via a truncated flag, and the presence of next_projection. This is exactly the kind of context annotations cannot express.

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 outcome and the value cap, then the auth clause, then the two year behaviors. It wastes a modest amount of space: "Needs sign-in to EconDash" restates the earlier signed-in clause, and the country ISO code sentence duplicates the schema description.

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?

With no output schema, the description still carries the return shape: same fields as get_indicator_series, plus next_projection and truncated. The cross-reference to a sibling's field set means the agent must consult that tool to know the exact payload, which is the only notable completeness gap.

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%, so the baseline is 3, but the description lifts it by explaining what omitting start_year/end_year does versus supplying them, including the range-and-truncation semantics that the schema's one-line field descriptions do not convey. It repeats the schema's ISO 3166-1 alpha-3 note for country, which adds nothing.

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?

"Returns the whole history of one indicator for one country or region" names a specific verb, resource, and scope, and immediately frames the distinction from get_indicator_series by volume (up to 1500 values). An agent can tell exactly what this call produces without opening the 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?

It states the access precondition (full data access vs. capped at get_indicator_series) and describes the two usage modes: no years for full history with the next projection, years for a bounded range. What it lacks is an explicit steer like "use get_indicator_series if you only need recent values" or an exclusion for indicators without projections, but the context is clear.

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