Three well-named, read-only tools with clear descriptions (avg 180 chars, within baseline 194). All tools have complete input schemas with typed properties and descriptions. search_materials and stable_phases lack 'required' arrays (should declare composition/element_set and elements as required). Output schemas are not documented, LLMs cannot predict response structure for chaining. Error handling is minimal (generic catch-all). No tool annotations (readOnlyHint, idempotentHint). Parameter descriptions are good (avg 85 chars) but lack format constraints (e.g., 'dash- or comma-separated' for elements should be an enum or pattern). Overall solid foundation with gaps in output documentation and validation guidance.

• Document output schemas for all three tools. Example for search_materials: 'Returns array of objects with fields: name (string), entry_id (number), formation_energy_ev_atom (number|null), stability_ev_atom (number|null), is_stable (boolean|null), band_gap_ev (number|null), spacegroup (string), prototype (string), n_element_types (number).'
• Add 'required' arrays: search_materials requires ['composition' OR 'element_set'] (use oneOf in schema); stable_phases requires ['elements']. Use JSON Schema oneOf/anyOf to express OR logic.
• Add tool annotations to inputSchema: readOnlyHint: true and idempotentHint: true for all three tools. This signals to agents that calls are safe to retry.
• Replace prose format constraints with JSON Schema patterns or enums. For element_set, add pattern: '^[A-Z][a-z]?(-[A-Z][a-z]?)*$' or document valid syntax more formally. For elements, add pattern: '^[A-Z][a-z]?([,-][A-Z][a-z]?)*$'.
• Enhance error handling: categorize errors (e.g., 'invalid_input', 'not_found', 'api_error') and include recovery hints. Example: 'Invalid composition "Fe2O3x": must match stoichiometry pattern. Try search_materials with element_set="Fe-O" instead.'