Server exposes 10 tools with basic schemas and descriptions, but significant quality gaps limit production readiness. Tool naming mixes action verbs with generic terms (opencode_runs, opencode_sessions). Descriptions are present but brief (avg ~60 chars, below 194-char baseline). Parameter descriptions exist but lack constraint details (enums, ranges, formats). No documented output schemas. Error handling and recovery guidance absent. Legacy aliases (tools 6-9) duplicate functionality without clear deprecation path. Tool composition issues: opencode_runs bundles start/status/list/cancel into one tool via action parameter; opencode_sessions combines 8 operations (list/get/messages/send/diff/rename/delete/export) into a single tool, violating single-responsibility principle.

• Split opencode_sessions into 8 separate tools: get_session, list_sessions, get_session_messages, send_session_message, diff_sessions, rename_session, delete_session, export_session. Each should have a clear verb_noun name and single responsibility.
• Add enum constraints to all 'action' parameters. Replace free-form strings with {"type": "string", "enum": ["start", "status", "list", "cancel"]} to prevent hallucinated actions.
• Document output schemas for all tools. Include response field names, types, and whether fields like job_id, session_id, or run_id are present. This enables LLM chaining.
• Add parameter constraints: specify ranges for numeric params (e.g., limit 1-100), formats for dates (ISO 8601), and required vs optional fields. Current descriptions lack actionable constraints.
• Remove or clearly deprecate legacy aliases (run_agent, get_run_status, list_sessions, get_session). If kept, add a deprecation notice and migration path to canonical tools.