Server provides 7 tools with complete input schemas and descriptions in Portuguese. Naming follows verb_noun pattern (issue_card, authorize, get_card, etc.). Descriptions are detailed (100-250 chars) and explain purpose, prerequisites, and return values. However, schemas lack parameter descriptions, only type and required fields are present. No output schemas documented. Error handling is implicit (HTTP status codes) but lacks recovery guidance. Tool composition is sound: each tool has one responsibility, and outputs contain IDs for chaining (cardId for authorize, etc.). Risk annotations (WRITE, DESTRUCTIVE, READ_ONLY) are present but not formalized in schema. STDIO transport caps protocol readiness.

• Add description field to every parameter in input schemas. E.g., holder: {type: 'string', description: 'Cardholder name. Cannot be empty. Used for card identification and statements.'}
• Document output schemas for each tool. Specify response structure: {id: string, holder: string, limitCents: integer, usedCents: integer, availableCents: integer, status: string} for get_card, etc.
• Enhance error descriptions with recovery paths. E.g., authorize description: 'Returns 404 if card not found, call issue_card() first to create a card. Returns 402 if insufficient limit, check available balance with get_card().'
• Formalize risk annotations using MCP toolAnnotations. Add readOnlyHint: true to get_card and health; destructiveHint: true to reset; idempotentHint: true to authorize (same input = same result).
• Migrate from STDIO to HTTP+SSE or Streamable HTTP transport to enable remote access and hosted client integration.