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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds useful behavioral context: 'Returns up to 10 results with English/Spanish names' and 'Omit search to get all countries.' This goes beyond the annotations without contradicting them.

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 redundant: the opening paragraph is repeated verbatim under the 'When to use' heading, and the parameter section adds no new information. While the first sentence is clear, the duplication wastes space and could be condensed to a single concise version.

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 the tool's simplicity (one optional parameter, no output schema), the description covers the key aspects: search term types, return limit, language options, and the behavior when search is omitted. It is sufficiently complete for an agent to invoke 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% and the description's parameter section merely restates the schema's description for 'search.' No additional meaning is provided beyond the schema, so the baseline of 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?

The description clearly identifies the tool's function: 'Search countries by name, international dial code, or ISO abbreviation.' It specifies the resource (countries) and the types of search terms, distinguishing it from sibling tools like fetch_areacodes and fetch_states. The 'Returns up to 10 results' statement adds scope.

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 'When to use' section provides clear context, explaining search by country name, dial code, or ISO abbreviation, and notes that omitting search returns all countries. It lacks explicit exclusions or alternatives to sibling tools, but the resource-specific language inherently guides selection.

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