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

Beyond the read-only/idempotent annotations, the description discloses important behavior: it returns specific violations rather than a boolean, and explicitly states the scope (required + types only) while disclaiming full JSON Schema support. This adds substantive context not captured by 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?

Four sentences, each with a distinct purpose: what it does, what it returns, its limitations, and when to use it. No wasted words; the information is front-loaded and efficiently delivered.

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?

The tool is simple (2 params, one required) and has a full output schema, so the description does not need to explain return values. It covers the essential behavioral aspects (parsing, optional key/type checks, violation reporting, and scope limitations) adequately for an agent to use 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?

The schema already provides 100% coverage for both parameters, with descriptions for 'text' and 'schema' including details about required[] and properties[].type. The description adds only a mild restatement of the schema's functionality ('required keys are present with the right top-level types'), not significantly new meaning, so it meets the baseline of 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 uses a specific verb ('Checks that text parses as JSON') and clearly states the resource (text) and optional key/type validation. It distinguishes itself from siblings like json_yaml by specifying it validates JSON and explicitly scopes to required keys and types, not full JSON Schema.

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 gives an explicit use case ('Use before feeding generated JSON into something that will fail on it') and a clear limitation ('not full JSON Schema'), implying when not to use it. However, it does not name an alternative tool for full schema validation, so it falls short of the full when/when-not/alternatives guidance.

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