ZeroMCP provides three tools with minimal documentation. All tools have descriptions (10-30 chars), but they are too brief to guide LLM selection effectively. Input schemas are present with basic type information (number, string) but lack parameter descriptions entirely, a critical gap. No output schemas are documented. The 'add' and 'hello' tools are trivial examples; 'create_invoice' is the only substantive tool but lacks guidance on required fields, error cases, or side effects. No error handling patterns are evident. Tool names follow verb_noun convention (add, create_invoice, hello) but descriptions do not explain WHEN to use each tool or what happens on failure.

• Expand each tool description to 50-150 characters. For create_invoice: 'Create a new invoice for a customer. Requires valid customer_id and amount in cents. Returns invoice_id and status. Fails if customer not found or amount invalid.'
• Add descriptions to all parameters. E.g., 'a: First number (integer or float)' and 'b: Second number (integer or float)' for add; 'customer_id: Unique customer identifier (string, required)' and 'amount: Invoice amount in cents (positive integer, required)' for create_invoice.
• Document output schemas for each tool. E.g., add returns {result: number}; create_invoice returns {invoice_id: string, status: string, created_at: string}.
• Add error handling guidance to create_invoice description: 'Returns error if customer_id not found or amount <= 0. Errors are retryable if status is 5xx; user-fixable if customer not found.'
• Consider adding enums or range constraints. E.g., amount must be > 0; status field could be enum [pending, sent, paid, cancelled].

Inferred effective spec: 2026-07-28+.

• Relies on Roots (deprecated) - pass files/dirs via tool parameters, resource URIs, or configuration