Reverse lookup: given an ATT&CK T-code, return D3FEND defenses that mitigate it. This is the bridge from offensive intelligence (ATT&CK / ATLAS / CVE) to defensive playbook. Pair with cve_lookup or atlas_technique_lookup output — when those carry an ATT&CK id, call this tool to surface the mitigations. defenses is capped at limit (default 30) for token efficiency; total is the honest pre-truncation count and truncated=true flags when the cap was hit. coverage_by_tactic always aggregates the FULL set, not the slice. Default response is SLIM (drops uri from each row); pass include='full' for the verbose record. Pass exclude_id when drilling from d3fend_defense_lookup to skip self in the 'see also' list. Returns 200 with empty defenses list when the T-code has no D3FEND mapping (the gap is itself a signal). Free: 30/hr, Pro: 500/hr. Returns {attack_technique_id, total, truncated, defenses [{defense_id, label, uri (only when include=full), parent_label, tactic, artifact, attack_label, attack_tactic}], coverage_by_tactic, next_calls}.
