Strong foundation with 12 well-named, read-only tools covering a coherent Allo API surface. All tools have descriptions (avg 150 chars, within baseline 194). Input schemas are present and properly typed with enums and constraints. Pagination parameters (page, size) are consistently implemented with min/max bounds. However, output schemas are not documented, LLMs cannot predict response structure for downstream chaining. Error handling is basic (HTTP status codes mapped to text) but lacks recovery guidance. No tool annotations (readOnlyHint, idempotentHint) despite all being read-only. Parameter descriptions are adequate but could be more prescriptive about expected formats and dependencies.

• Document output schemas for all tools. For allo_search_calls, formally specify: {calls: [{id, transcript: [{source, text, time, start_seconds, end_seconds}], summary, recording_url, tags, type, result}], total_count, page, size}. This enables LLMs to extract and chain data correctly.
• Add tool annotations: mcp.WithReadOnly() and mcp.WithIdempotent() to all 12 tools. This signals to LLMs that these calls are safe to retry and do not modify state.
• Enhance error messages with recovery hints. In respond(), detect 404 errors and suggest relevant discovery tools: 'Contact not found. Try allo_search_contacts() to find the correct contact_id.'
• Standardize pagination to 0-indexed across all tools. Update allo_list_conversations to use page=0 as default instead of page=1. Document in tool descriptions: 'Page is 0-indexed. Default 0.'
• Add regex pattern constraints to phone number parameters. Declare allo_number as pattern: '^\+[1-9]\d{1,14}$' (E.164) in the schema, and reference it in descriptions: 'E.164 format: +[country][number], e.g. +14155551234.'