require-type-param-tags

Require @typeParam tags for documented generic declarations.

Targeted pattern scope

This rule checks documented declarations that declare generic type parameters:

• function declarations and declared functions,
• methods,
• classes,
• interfaces,
• type aliases.

What this rule reports

This rule reports missing type-parameter tags when a declaration has type parameters but its TypeDoc block omits one or more @typeParam entries.

Why this rule exists

Generic APIs are harder to consume when type parameters are undocumented. This rule ensures generated docs explain each generic parameter's intent.

❌ Incorrect

/**
 * Map one value into another type.
 * @typeParam TInput Input type.
 * @param input Input value.
 * @param mapper Mapping function.
 * @returns Mapped value.
 */
export function mapValue<TInput, TOutput>(
    input: TInput,
    mapper: (value: TInput) => TOutput
): TOutput {
    return mapper(input);
}

✅ Correct

/**
 * Map one value into another type.
 * @typeParam TInput Input type.
 * @typeParam TOutput Output type.
 * @param input Input value.
 * @param mapper Mapping function.
 * @returns Mapped value.
 */
export function mapValue<TInput, TOutput>(
    input: TInput,
    mapper: (value: TInput) => TOutput
): TOutput {
    return mapper(input);
}

Behavior and migration notes

Autofix inserts TODO @typeParam entries for missing generic parameters directly into the existing doc block.

ESLint flat config example

import typedocPlugin from "eslint-plugin-typedoc";

export default [
    {
        plugins: { typedoc: typedocPlugin },
        rules: {
            "typedoc/require-type-param-tags": "error",
        },
    },
];

When not to use it

Disable this rule when your API style intentionally avoids per-generic prose and relies solely on type signatures.

Package documentation

TypeDoc package documentation:

• TypeDoc @typeParam tag

Further reading

Rule catalog ID: R007

• TypeDoc comments and tags

Adoption resources

• Enable this rule after require-param-tags/require-returns-tag for full generic API coverage.