This is a well-structured MCP server with clear, production-focused tool definitions. All 5 tools have explicit schemas, descriptions, and parameter types. Tool names use consistent verb_noun patterns (convert_*, get_*, list_, set_). Descriptions are concise and actionable, ranging 90-280 chars. Parameters are typed with enums, ranges, and detailed descriptions. Output schemas are documented through Pydantic models. Error handling includes actionable guidance (e.g., suggesting alternative approaches when a resource is not found). The main gaps are: (1) lack of tool annotations on most tools (only some tools have read_only_hint, destructive_hint, idempotent_hint defined in code), (2) error taxonomy not explicitly in tool descriptions (though implemented in code), and (3) some parameters like 'timeout_seconds' have rationale in descriptions but could be clearer about retry semantics. Schemas are complete and JSON-serializable. Security is handled properly via OAuth middleware (credentials not exposed as parameters). The tool set is well-composed: convert_bank_statement (write), get_conversion (read, idempotent), list_conversions (read, paginated), get_account_balance (read), set_output_folder (write, stateless config). This is a B+ server, excellent domain coverage and clarity, minor gaps in annotation metadata exposure.

• Ensure tool_annotations (readOnlyHint, destructiveHint, idempotentHint) are serialized in the MCP tool_list response so LLMs see them. Verify the MCPServer base class includes these in the JSON when tools are registered.
• Enhance get_account_balance description to document the returned fields: 'Returns the account balance with fields: page_credits (integer), account_status (string), ...'
• Add explicit error recovery guidance to convert_bank_statement and get_conversion descriptions: 'If timeout_seconds expires before conversion completes, the job continues running. Call get_conversion(job_id) to poll for results.' Include a note on job_id persistence.
• Clarify timeout behavior in parameter descriptions: 'Timeout leaves the job running server-side and returns a job_id that can be used with get_conversion to retrieve results asynchronously.'
• Update set_output_folder description to clarify state mutation: 'This tool is idempotent, calling it multiple times with the same path has no additional effect. The folder path persists across all subsequent calls in the same session (stdio) or is ignored (HTTP mode, which is stateless).'
• Consider adding a 'Dry Run' or confirmation flow to convert_bank_statement since it consumes page credits. E.g., a preview_conversion tool that estimates usage without spending credits.
• Document pagination behavior for list_conversions: 'Returns up to `limit` jobs; if more exist, a non-empty `cursor` is returned. Pass it to the next call to fetch the next page. An empty cursor means end of list.'