Server has 15 tools with basic definitions present. Most tools follow verb_noun naming conventions (search_*, get_*), which is correct. However, the implementation exhibits significant gaps in definition quality: (1) Parameter descriptions are minimal and sometimes missing details about format/constraints. For example, 'season_id' in get_club_players is described as 'Optional season identifier for filtering' but lacks examples of valid formats. (2) Output schemas are NOT documented anywhere in the provided source code, there is no JSON schema definition, response structure documentation, or field description for what these tools return. The client.py makes raw API calls and returns whatever the Transfermarkt API sends, but the MCP tool definitions do not specify what fields LLMs should expect. (3) Error handling is present in the client (timeout, connection errors, HTTP errors) but messages are generic ('Request timed out', 'Failed to connect') without actionable recovery guidance. (4) Several tools appear redundant: get_player_by_id and get_player_profile both take player_id and likely return similar data, this violates single-responsibility and confuses the LLM. (5) No pagination documentation in search tools despite page_number parameter. (6) Descriptions are terse, most are 40-80 characters, which meets the floor but lacks the 'WHEN to use this vs similar tool' guidance that LLMs need for proper selection.

• Document complete output schemas for every tool. Specify fields, types, and descriptions. Example: 'search_clubs returns {results: [{club_id: string, name: string, founded: number, country: string}], total_pages: number, current_page: number}'. This tells LLMs what to expect and enables chaining.
• Merge get_player_by_id and get_player_profile into a single get_player tool, or clearly differentiate them with distinct descriptions and different response structures. Right now they are confusingly similar.
• Enhance error messages with actionable guidance. Replace 'Request timed out' with 'Request timed out after 30 seconds. The API may be temporarily unavailable. Retry in 10 seconds or contact the Transfermarkt API status page.'
• Add format constraints to optional parameters. For season_id, specify: 'Optional season identifier in format YYYY/YYYY (e.g., 2023/2024) or API season_id integer. If omitted, returns the current season.'
• Document pagination behavior in search tool descriptions. Example: 'Returns up to 50 results per page. Use page_number to iterate. Response includes total_pages for planning subsequent calls.'
• Add readOnlyHint annotations to all tools. In fastmcp, this can be done via tool metadata (e.g., @mcp.tool(readOnlyHint=True)) to signal these are safe, retryable operations.
• Expand tool descriptions to 80-150 characters and include discovery guidance. Example for search_clubs: 'Search for clubs by name. Use this to find a club when you have a partial name. Returns paginated results; use get_club_profile to fetch full details for a specific club_id.'

Inferred effective spec: <=2025-11-25.

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry