Three tools with functional but minimal schema and description quality. All tools have descriptions (passing basic bar), but they are generic and lack detail about error conditions, data structures, and recovery paths. Input schemas are present but extremely sparse, only one string parameter per tool with minimal type information. No output schemas are documented anywhere in the code. Naming is verb-based (parse, validate, compare) which is good, but parameter descriptions are one-liner and do not explain formats, constraints, or expected values. No examples of error handling, validation guidance, or actionable recovery instructions. This is typical of a STDIO-only server focused on minimal functionality rather than LLM ergonomics.

• Add detailed output schemas for each tool. E.g., parse should return { invoice_number, issued_date, due_date, seller_name, buyer_name, total_amount, line_items: [{description, quantity, unit_price, tax_rate}], format, profile }. Validate and document this with examples.
• Expand 'path' parameter description to: 'Absolute or relative filesystem path to invoice file. Supported formats: .pdf (Factur-X/ZUGFeRD), .xml (UBL/CII/XRechnung). Max 10 MB. Required.'
• Rewrite tool descriptions to 100-200 chars, explaining use cases and differences. E.g., 'Parse an invoice file to extract structured invoice data (invoice number, amounts, line items). Use parse to load raw data; use validate to check compliance; use compare to detect PDF-XML mismatches.'
• Add error handling guidance: Document expected errors (file not found, invalid format, API timeout, API rate limit, invalid API key) and recovery actions for each.
• Add tool annotations: mark all three tools with readOnlyHint=true since they do not modify state.
• Add per-parameter constraints: Declare 'path' format as file path pattern, add enum constraint for file extensions (.pdf, .xml), document max file size (10 MB) in schema.
• Document the structure of the 'parse' tool response with sample fields: { format: string (e.g., 'Factur-X'), profile: string, invoice_number: string, issued_date: ISO8601, due_date: ISO8601, seller: { name: string, id: string }, buyer: { name: string, id: string }, line_items: [{description: string, quantity: number, unit_price: number, tax_rate: number}], total_excl_tax: number, tax_amount: number, total_incl_tax: number }