Four well-named, read-only tools with clear descriptions (avg 180 chars, within baseline 194). All tools have complete input schemas with type definitions and required fields. Naming follows verb_noun pattern (search_, get_, list_). Parameter descriptions are present and actionable. Output schemas are not explicitly documented in the code, which is a notable gap. Error handling returns structured objects with error fields but lacks recovery guidance. No tool annotations (readOnlyHint, etc.) despite all being read-only. Missing output schema documentation and recovery hints prevent a higher score.

• Add formal output schema documentation for each tool. Example for search_studies: 'Returns {count: number, studies: [{study_id: string, name: string, cancer_type: string, samples: number, pmid?: string, reference_genome?: string}]}'.
• Declare readOnlyHint=true in tool definitions. Update McpToolDefinition interface to include optional annotations field and set it for all four tools.
• Enhance error responses with recovery hints. When get_study returns 404, append: 'Try search_studies(query="<partial_name>") to find available studies.'
• Clarify search_studies behavior when query is omitted. Specify: 'If query is omitted, returns up to limit studies in alphabetical order by study_id.'
• Document pagination behavior. Add to search_studies and list_cancer_types descriptions: 'Results are limited to the specified limit; call again with offset or pagination cursor if more results exist.' (Note: current implementation does not support offset/cursor; consider adding for production use.)