Single tool 'check_usage' has a reasonable description (89 chars, within 10-1024 range) but CRITICAL deficiency: input schema is completely empty ({}). Tool definition is inferred from cli_test.go rather than explicit MCP registration in source. No parameter descriptions, no output schema documentation, no error handling guidance. Tool naming is acceptable (verb_noun pattern: 'check_usage') but cannot overcome schema absence.

• Define explicit input schema with JSON Schema types and descriptions for any parameters (e.g., if caching behavior or output format is configurable).
• Document the output schema: what fields does check_usage return? (e.g., remaining_budget, reset_date, window_name, severity). Include types and descriptions for each field.
• Add error handling guidance: 'If the usage endpoint is unavailable, the tool returns cached data with an age field. If no cache exists, it returns an error with retry guidance.'
• Move tool registration from test file into explicit MCP server code (mcp.go or similar) with full schema and description inline.
• If the tool supports optional parameters (e.g., --json output format, --fields selection), expose them as optional input parameters with enum constraints and descriptions.