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

With readOnlyHint=true already declaring a safe read operation, the description adds substantial non-obvious behavior: billing of 2 credits per successful call, rejection before billing on schema mismatch, and the exact shape of the validation result. Nothing contradicts the 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?

The description is two compact sentences. The core purpose and validation scope are front-loaded, and the billing and return-shape details follow without padding.

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: one required input and no output schema. The description compensates by naming exactly what gets validated and by describing the return structure (ok, events, hookCount, findings, counts), so an agent has everything needed to invoke and interpret it.

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?

There is only one parameter, and the schema fully documents it as a JSON string or object up to 60,000 characters. The description adds the useful scope that the input can be a hooks block or a whole settings.json, but does not otherwise elaborate on the parameter beyond the schema's own description.

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 specific verb (validates) and a clearly scoped resource: a Claude Code hooks block or an entire settings.json. It also enumerates the checked dimensions (events, matchers, hook types, timeouts, risky commands), which distinguishes it from validator siblings such as mcp-config-validate or json-validate.

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?

Usage is implied by the resource named: use this for Claude Code hooks configuration. However, the description does not explicitly say when to choose it over related siblings (e.g. json-validate, mcp-config-validate, claude-md-lint), nor does it state exclusions or prerequisites.

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