Checks if a string contains valid JSON, returning a boolean result for parsing validation. Use it to verify JSON text before processing or storing it.
Check whether a string is valid JSON.
| Name | Required | Description | Default |
|---|---|---|---|
| text | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v1.0.4Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full disclosure burden. It states the boolean-check nature but says nothing about strictness of validation (trailing commas, duplicate keys), behavior on empty/large input, or that it is a pure read. For a simple deterministic validator this is tolerable but still thin.
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 tight sentence with no filler; purpose is front-loaded. Efficient, though almost to the point of under-specification rather than true conciseness.
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?
An output schema exists, so return values need not be explained, and the operation is simple. Still, the definition gives no information on validation semantics or the single parameter, leaving modest gaps for an agent to call and interpret it 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?
One parameter ('text') with 0% schema description coverage. The description mentions 'a string', which merely restates the schema's declared type and adds no format or edge-case meaning. It does not compensate for the coverage gap.
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: 'Check whether a string is valid JSON.' An agent can immediately understand the operation. However, it does not explicitly differentiate from the many sibling validators (validation_is_email, validation_is_url, etc.), though the resource word 'JSON' makes the scope self-evident.
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?
No indication of when to use this tool versus alternatives, no prerequisites, no exclusions. The description offers zero routing guidance beyond the self-descriptive name.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.