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

The annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint false, covering the safety profile. The description adds the data source (HDX CKAN Action API) and that no auth is required, which is useful behavioral context. However, it doesn't disclose additional details like pagination or the exact format of the returned count. Given annotation coverage, a 3 is appropriate – it adds some context but not rich behavioral disclosure.

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 three concise sentences, each earning its place: purpose, usage hint, and data source/auth. It is front-loaded with the primary function and avoids any fluff. No redundancy or irrelevant details. This is an efficient, well-structured 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?

Given that an output schema exists, the description doesn't need to explain return values. It covers the purpose, the parameter filtering behavior, the downstream usage (location ID for dataset search), and the data source. It hints at the dataset count in the output, which is helpful. The only minor gap is not explicitly stating the default behavior when no query is provided, but that's implied. Overall, it's sufficiently complete for an agent to call correctly.

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%; both `limit` and `query` have clear descriptions in the schema. The description adds a slight clarification that the query is a substring filter, but this is already in the schema. It does not compensate for any missing schema info since none is missing. The description also references the output usage, not the parameters, so it adds minimal extra meaning beyond the schema. Baseline 3 is correct.

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 clearly states the tool lists countries/regions tracked on HDX with their published dataset count, and optionally filters by name substring. It uses a specific verb ('List') and resource ('countries/regions tracked on HDX'), making the purpose unambiguous. It also mentions the data source and that no auth is required, which adds clarity. Though it doesn't explicitly differentiate from sibling reference tools, the resource type is distinct and the downstream use case is 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 description provides a clear use case: use the returned location id as the `country` filter for hdx.dataset_search. This implies when to use it (when you need a location ID for dataset search) and gives context. However, it does not explicitly discuss alternatives like hdx.reference.organizations or when NOT to use this tool. The guidance is implied rather than explicit, so it falls short of a top score.

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