The server provides 26 tools with mostly complete input schemas and descriptions, but significant gaps exist. Naming follows the verb_noun convention consistently (create_lead, get_lead, list_leads, etc.), which is correct. Descriptions are present for all tools and most parameters, averaging ~80-120 characters, acceptable but some are sparse. Parameter descriptions are generally adequate but could be more prescriptive about valid values and constraints. Critical issues: (1) Tools 11 and 12 (instantly_create_campaign, instantly_update_campaign) have empty schemas ({"type":"object"} with no properties), rendering them unusable, schema score 0 for both. (2) Most tools lack enum constraints for values like 'status' in list_campaigns (status param accepts 0-4 but only described in text, not as enum). (3) No output schemas documented anywhere, LLMs cannot plan downstream calls. (4) Error handling returns plain text errors without recovery guidance or categorization. (5) Some parameter descriptions lack format specs: 'phone' accepts any string, no validation pattern; 'list_id' and 'campaign' are described as UUID but not validated; date parameters in get_campaign_analytics lack format specification. (6) The custom_variables parameter (in create_lead) is typed as object but has no schema for its properties. (7) No per-tool documentation of what fields are returned, what UUIDs can be used where, or how to chain tools (e.g., what ID does create_lead return?). Positive: tool naming is clear and action-oriented; descriptions exist for all tools; parameter typing is mostly present; error handling uses isError flag; tool annotations are present (Risk levels declared). The server is functional but would not pass production code review for agent tooling.

• Add complete input schemas to instantly_create_campaign and instantly_update_campaign. Document every field (name, description, subject, body, etc.) with type, description, and whether it is required.
• Document output schemas for all 26 tools. For each tool, specify what fields are returned in the response. E.g., create_lead should return {lead_id, email, first_name, last_name, created_at}. This enables LLMs to chain calls and plan multi-step actions.
• Convert text-based enum descriptions to JSON Schema enum declarations. E.g., for status in list_campaigns, use {"type": "number", "enum": [0, 1, 2, 3, 4], "description": "..."} instead of describing values in text.
• Enhance error responses with categorization and recovery guidance. Return structured errors: {"isError": true, "errorType": "retryable" | "user_fixable" | "fatal", "message": "...", "suggestion": "..."}. E.g., 'Lead not found. Try search_leads() with a partial name.' instead of 'Error retrieving lead'.
• Add format constraints and validation rules to all date, phone, URL, and ID parameters. Use JSON Schema format, pattern, minLength, maxLength, and describe in parameter descriptions. E.g., {"type": "string", "format": "date", "pattern": "^\d{4}-\d{2}-\d{2}$"}.
• Define the custom_variables schema. Specify what keys are valid, what types each should be, and provide examples. E.g., {"type": "object", "properties": {"custom_field_1": {"type": "string"}, ...}, "additionalProperties": true}.
• Document idempotency for all write and destructive operations. Add a note to tool descriptions: 'Idempotent: Safe to retry. Calling with the same lead_id and parameters will not create duplicate records.' or 'Non-idempotent: Each call merges leads. Retry may result in unexpected state.'