Three well-named, read-only tools with complete Zod schemas and detailed descriptions. All tools follow verb_noun pattern (search_, get_). Descriptions are substantive (150 - 250 chars), explaining what each tool does, when to use it, and what it returns. Input schemas are fully typed with enums, ranges, and parameter descriptions. Error handling uses custom MarktplaatsError class with actionable messages. Tool annotations (readOnlyHint, openWorldHint) are present. Main gaps: output schemas are not formally documented (only visible via JSON response structure), no pagination guidance for search_listings despite accepting limit/offset, and error recovery paths could be more explicit.

• Document output schemas as TypeScript interfaces or JSON Schema in code comments. E.g., search_listings returns {listings: [{id, title, priceEur, condition, delivery, ...}], count: number}.
• Add pagination guidance to search_listings: 'Marktplaats does not return total count. Iterate with offset until fewer than limit results are returned.'
• Enhance error messages with recovery paths. E.g., fail() should return: 'Listing not found. Try search_listings(query="...") to find valid IDs.' instead of bare error text.
• Clarify sellerId parameter in get_seller: 'Numeric seller ID (preferred) or string coerced to number. E.g., 57429132 or "57429132".'
• Add tool annotation for search_listings: consider adding destructiveHint: false explicitly to reinforce read-only semantics, though readOnlyHint already covers this.