Single tool 'shorten' has a basic description and input schema, but critical gaps prevent production use. Description is adequate (58 chars) but lacks WHEN to use it, prerequisites, or what it returns. Input schema exists with type and description, but output schema is completely undocumented, LLMs cannot plan downstream actions. No error handling guidance, no parameter constraints (URL format validation happens server-side, not declared), and no mention of rate limits or API dependencies. Tool is read-only but lacks explicit idempotent annotation. The implementation shows good defensive coding (URL validation, self-shortening prevention) but none of this is surfaced in the tool definition for LLM reasoning.

• Add output schema documentation: 'Returns object {shortUrl: string (the shortened kool.ink link), originalUrl: string, createdAt: ISO8601 timestamp}' so LLMs know what to expect.
• Expand tool description to 100-150 chars: 'Shorten any HTTP(S) URL to a clean kool.ink link. Returns a short URL string ready to share. Use when you need compact links for chat, SMS, or social media. Free, unlimited, no signup required.'
• Add error recovery guidance: 'If the URL is already a kool.ink link, inform the user it cannot be shortened further. If API returns 429 (rate limit), retry after 60 seconds. If API is unavailable, suggest trying again later.'
• Add idempotentHint: true to the tool schema so LLMs know it is safe to retry without side effects.
• Add format constraint to url parameter: 'format': 'uri' or a pattern regex in the JSON Schema, plus description: 'Must be a valid HTTP or HTTPS URL (e.g., https://example.com/path). URLs already pointing to kool.ink will be rejected.'