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

Annotations already mark this as read-only (readOnlyHint=true). The description adds that it 'report[s] parsing errors', giving insight into its behavior (output includes error details). This is useful context beyond the annotation, though it does not specify the exact return structure.

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?

A single, front-loaded sentence that clearly states the purpose and behavior. No filler or redundancy. It wastes no words and achieves exactly what the description needs.

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 this is a one-parameter tool with full schema coverage, strong purpose clarity, and a read-only annotation, the description is reasonably complete. It mentions error reporting, providing some insight into the return value, though without an output schema it could further clarify the success/error response format. Overall, it is sufficient for the tool's simplicity.

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 input schema covers 100% of the parameter with description 'JSON string to validate'. The tool description essentially repeats this ('Validate whether a string is valid JSON') without adding new meaning or clarifying edge cases (e.g., error format, empty strings). With full schema coverage, the baseline is 3.

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 states a clear, specific action: 'Validate whether a string is valid JSON and report parsing errors.' It uses the verb 'validate', identifies the resource (JSON string), and distinguishes itself from sibling tools like text_json_format or text_json_to_yaml by focusing on validation.

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 usage context is implied: use this when you need to check if a string is valid JSON. However, no explicit alternatives or 'when not to use' guidance is provided, even though sibling tools like text_json_format exist. It is not misleading, but it does not actively steer the agent away from other tools.

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