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

Annotations already cover the safety profile (readOnlyHint=true, openWorldHint=false, destructiveHint=false), so the description's added value is the 7-day window, the single-source constraint ("reads only the OONI index"), and the low-confidence flag — all real behavioral context an agent can't get from annotations. It stops short of saying what happens for a country with sparse or missing index data.

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 sentences, zero filler, with the returned-field inventory front-loaded and the scope caveat immediately after. Every clause earns its place.

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 correctly compensates by enumerating the five returned fields, which is the critical missing piece. It is slightly under-specified on failure/empty-index behavior and on the freshness semantics of the ingestion timestamp, but is otherwise complete for a one-parameter read.

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?

The single parameter has 100% schema coverage including the ISO 3166-1 alpha-2 pattern and uppercase requirement, so the schema carries the semantics. The description only obliquely references the parameter as "one country's" and adds no format or edge-case guidance beyond the schema. Baseline 3 applies.

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 ("Returns one country's 7-day OONI index signal") and enumerates exactly what the payload contains: score 0-100, rank, measurement count, low-confidence flag, ingestion time. The second sentence scopes it against sibling territory (incident details, per-measurement citations belong elsewhere), but no sibling is named explicitly.

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 exclusion sentence implicitly tells the agent not to come here for incident detail or citations, which implies the use case (a quick single-country index snapshot). However, it never says when to prefer this over close siblings like get_country_profile, get_country_status, or get_atlas_score, leaving the routing decision to inference.

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