The MusicBrainz MCP server provides 22 read-only tools with mostly consistent naming (verb_noun pattern: search_*, get_*, browse_*) and clear descriptions. However, there are critical gaps: (1) Output schemas are not visible in the source code, only input schemas are documented. (2) Many parameters lack type specifications or descriptions. (3) Error handling is minimal, with generic fallback messages rather than actionable recovery guidance. (4) No tool annotations beyond read-only hints. The tools are well-structured for pagination (limit/offset), but the lack of documented output schemas and incomplete parameter details prevent a higher score. The server demonstrates good naming hygiene and reasonable descriptions (100-150 chars on average), placing it in the 'fair' range.

• Document complete output schemas for all 22 tools. Include field names, types, and descriptions for each response object. Example: browse_entities should return {entities: [{id: string, name: string, type: string}], count: number, offset: number, limit: number}.
• Add structured error responses with categorization. Instead of 'An unexpected error occurred', return: {error: 'not_found', message: 'Artist with ID xyz not found', suggestion: 'Try search_artists() with the artist name'}.
• For get_artist_details, replace the freeform 'includes' array with an enum: ['releases', 'recordings', 'relationships', 'tags', 'ratings']. Document what each include adds to the response.
• Ensure tool_annotations are correctly applied during tool registration. Verify that idempotentHint and readOnlyHint are both present in the MCP protocol messages for all tools.
• Add a limits/pagination section to all search and browse tool descriptions. Clarify that 'limit defaults to 5/25 and max is 100' to prevent LLMs from requesting unreasonable result counts.
• Implement Streamable HTTP as the primary transport and retire STDIO. This enables hosted client integrations and remote access. The http_server.py entry point is a good start, make it the default.
• Add recovery hints to 3-4 key tool descriptions. Example: get_artist_details should note: 'If you have only the artist name, call search_artists() first to get the ID.'
• Return MusicBrainz API errors verbatim when recoverable (e.g. 'Rate limited, retry in 60 seconds'), not generic messages. This helps LLMs understand the service state.