Avito MCP has solid naming conventions (all tools start with domain + verb, e.g. 'auth_get_access_token', 'messenger_send_message') and presents 23 tools across 6 domains. Tool descriptions are present but concise (averaging ~40-60 chars, below the 194-char production baseline). Parameter schemas are visible for most tools (items_get_item_info, messenger_get_chat_messages, reviews_reply_to_review all show explicit input types), but many tools lack visible schema details in the provided source excerpt. Error handling is implicit (confirmation_id/secret in meta_confirm_action suggests irreversible operations require confirmation, a good pattern), but recovery guidance in error messages is not evident from the source. Security is strong (OAuth token handling, no credentials in params). Output schemas are inferred but not explicitly documented. Tools are well-composed (each performs one domain action) and chain properly (e.g., messenger tools follow get → send pattern). The server supports both STDIO and HTTP transport, enabling remote accessibility.

• Expand tool descriptions to 50 - 200 characters minimum, following the LLM-optimized format: '[ACTION] [WHAT] [WHEN/WHY] [DEPS if any]'. Example: 'List your active marketplace items with filtering by category, status, and date range. Use before editing or promoting. Requires seller account.'
• Add parameter descriptions to every tool schema. For each parameter, document its type, valid values/ranges, expected format, and constraints. Example for 'text' param in messenger_send_message: 'Message text to send (plaintext or markdown, max 4096 chars, required, no HTML).'
• Document output schemas for all tools, especially list/get tools. Include field names, types, and which fields are safe to chain into downstream tools. For paginated results, document the pagination strategy (offset/limit or cursor), default/max page size, and total count field.
• Create explicit dry-run or confirmation workflow for irreversible operations. Document in promotion_create_campaign description: 'Creates and activates a campaign immediately (irreversible). Call with dry_run=true first to preview, or rely on meta_confirm_action for approval flow.'
• Improve naming clarity for list tools. Rename 'items_list_items' → 'items_list_my_listings' or 'items_list_seller_items'; 'orders_get_orders' → 'orders_list_my_orders'; 'reviews_get_reviews' → 'reviews_list_received_reviews'. This reduces ambiguity and makes the scope (user's data vs. marketplace search) explicit.
• Add error classification and recovery hints to tool implementations. Document which errors are retryable, which are user-fixable, and which are fatal. Include suggestions in error responses, e.g., 'Item XYZ not found. Available items: [list or call items_list_my_listings()].'

Inferred effective spec: <=2025-11-25.

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry