Materials MCP has severe definition quality gaps. Tool 'initialize' is a protocol-level concern, not a domain tool, it should not be exposed as a callable tool. The three domain tools (get_info, query_structures, get_structure_details) have minimal descriptions (10-50 chars, well below the 194-char baseline) and lack parameter descriptions entirely. No output schemas are documented. The server conflates MCP protocol mechanics with domain functionality, violating separation of concerns. No error handling guidance, no pagination metadata, no chaining IDs in responses.

• Remove 'initialize' from the tool list. MCP handles protocol initialization via the built-in initialize request, do not expose it as a domain tool.
• Document output schemas for all tools. For query_structures, specify: returns {data: [{id, attributes: {chemical_formula_reduced, formation_energy_per_atom, ...}}], meta: {total_count, next_cursor}}. For get_structure_details, specify all available material properties.
• Expand tool descriptions to 50-200 chars. Example: 'Query the GNoME database for stable materials matching a filter (e.g., formation_energy < -2.0). Returns up to page_size results with structure IDs and key properties. Use get_structure_details to fetch full data.'
• Add parameter descriptions and constraints. For filter_str: 'OPTIMADE filter string (e.g., "_gnome_formation_energy_per_atom < -1.0 AND nelements = 2"). See OPTIMADE spec for syntax.' For page_size: 'Results per page (1-100, default 10).'
• Add pagination and chaining metadata. query_structures should return next_cursor and total_count so agents can iterate. Include structure_id in results so agents can immediately call get_structure_details without a second lookup.