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

Descriptions explicitly state idempotency, repeating what the idempotentHint annotation already says, but also add the behavioral detail that it accepts region id or name plus country. The level parameter's default is not mentioned in the description, which is a minor gap, but idempotency is valuable and consistent with annotations.

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?

Extremely concise: two sentences. The purpose is front-loaded, and the idempotency note is useful without redundancy.

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 required param, no nested objects), the description is adequate. It lacks mention of the level parameter's default and the notes parameter, but these are documented in the schema. No output schema is expected for a mutation tool, so return value is not a 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 description coverage is 100%, so the schema fully documents all parameters. The description adds the alias between region and name, but the parameter descriptions are clear. The description does not explain the default behavior for 'level' beyond the schema's 'Default visited', which is already there.

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?

Clear verb-resource pair ('Mark ... as visited') and explicitly names the accepted inputs (region id or name plus country). This distinguishes it from siblings like add_country and add_place, though it does not explicitly name them.

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 implies usage for marking a region visited, but there is no explicit guidance on when to use this tool versus add_country or add_place, nor any discussion of prerequisites or constraints such as needing an existing trip.

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