TracePass MCP server demonstrates solid definition quality with well-documented tools, proper input schema structures, and thoughtful action-based design. All 6 tools have clear descriptions explaining their purpose and the actions they support. Input schemas follow a consistent pattern with action enums and args objects. Output schemas are explicitly documented with `.passthrough()` to handle action-specific variations. However, per-action schema details are delegated to handler validation rather than exposed in the inputSchema, creating a gap between declared and actual validation rigor. Error handling guidance is present in descriptions but lacks actionable recovery hints for common failure modes. Tool naming follows verb_resource convention well, though the single-parameter 'args' design limits schema introspection at the protocol level.

• Break the 'args' object into action-specific parameters in the schema. Instead of a generic object, use a discriminated union (action enum that narrows the args shape) or document each action's schema separately. E.g., for tracepass_products: 'action: list' requires [limit?, page?]; 'action: create' requires [name, model, ...]. This allows LLMs to see constraints upfront.
• Add per-action error guidance. For example, in tracepass_passport_fields, document: 'If fieldKey is invalid, the API returns a 400 with a list of valid keys. Call tracepass_templates get <category> to see the allowed fields for this passport type.'
• For billable actions (passport create, batch_create), add an explicit confirmation step. E.g., 'To create a passport, first call tracepass_passports action=create with dry_run=true to estimate quota usage, then call with dry_run=false to confirm.' Or mark with destructiveHint: true in annotations and explain quota implications in the description.
• Document output structure per action. In tracepass_passports, note: 'action=list returns {items: [...], total, page, limit, totalPages}; action=get returns {id, name, ...}; action=qr returns {result: "<svg>..." or "<base64-png>"}'.
• Expand the 'args' parameter description to enumerate per-action schemas inline. E.g., 'args object shape depends on action: {action: "create", args: {name: string, model: string, description?: string}}, {action: "list", args: {limit?: 1-100, page?: integer}}, ...'
• Add rate-limit and quota guidance to tool descriptions. Passport creation is billable, document typical costs and recommend batch_create for bulk operations.