Pyfastmail — the complete, unedited output of the deterministic mcptrustchecker engine v1.13.0, scanned . Every finding, capability tag and score component below is exactly what the engine produced — no AI, no post-processing.
{
"tool": {
"name": "mcptrustchecker",
"version": "1.13.0",
"methodologyVersion": "mcptrustchecker-1.13"
},
"target": {
"id": "pyfastmail-mcp",
"source": {
"kind": "package",
"origin": "pyfastmail-mcp"
},
"server": {
"name": "pyfastmail-mcp"
}
},
"grade": "A",
"score": {
"score": 93,
"threatScore": 100,
"grade": "A",
"band": "A",
"categorySubtotals": {
"injection": 0,
"exfiltration": 0,
"permissions": 0,
"supply-chain": 0,
"network": 0,
"hygiene": 0
},
"vector": [
{
"kind": "client",
"term": "capability-exposure",
"level": "high",
"label": "capability blast radius (high) — client exposure if the model is manipulated",
"appliedPenalty": 6
},
{
"kind": "client",
"term": "verification-discount",
"level": "repo",
"label": "publisher verification (public source) — no provenance, but the source is public and inspectable",
"appliedPenalty": 1
},
{
"kind": "client",
"term": "coverage-honesty",
"level": "source",
"label": "inspection depth (source) — how much of the target the scan could see",
"appliedPenalty": 0
}
],
"gatesFired": [],
"methodologyVersion": "mcptrustchecker-1.13"
},
"capability": {
"level": "high",
"reasons": [
"ingests untrusted external content (a prompt-injection entry point)",
"can send data / act on an external service",
"reads sensitive or local data",
"has a read → egress path (a data-exfiltration surface)",
"untrusted-input, sensitive-source and egress co-exist across tools (toxic-flow surface)"
],
"tags": [
"untrusted-input",
"sensitive-source",
"external-sink"
]
},
"coverage": {
"level": "source",
"inputs": {
"toolSurface": true,
"implementationSource": true,
"packageMetadata": true,
"liveTransport": false
},
"caveats": [
"Tools were statically extracted from the published source (48 recovered), not enumerated from a running server. Tool-poisoning, Unicode-smuggling, capability and toxic-flow analysis ran on this inferred surface, but a mis-parsed registration could be missed or mis-attributed, so tool-derived findings are capped below “confirmed”. To grade the real runtime surface, scan the running server: --command \"npx -y <package>\"."
]
},
"findings": [
{
"ruleId": "MTC-FLOW-002",
"title": "Completed toxic-flow trifecta across tools",
"category": "exfiltration",
"severity": "critical",
"confidence": "strong",
"description": "This server (without client built-ins) exposes a complete data-exfiltration chain: contacts_get_contact → files_list → mail_forward_email. Untrusted input is ingested, private data is read, and it can be sent to an external sink via the agent composing the tools (→). Static analysis proves the primitive exists, not that a specific run will occur.",
"remediation": "Remove one leg of the trifecta: isolate untrusted-input tools from secret-reading tools and from egress tools, or require human approval between them.",
"location": {
"kind": "flow",
"name": "contacts_get_contact → files_list → mail_forward_email"
},
"owasp": "LLM02:2025 Sensitive Information Disclosure",
"references": [],
"data": {
"untrusted": [
"contacts_get_contact",
"files_get",
"mail_download_attachment",
"mail_export_email",
"mail_parse_email"
],
"sources": [
"files_list"
],
"sinks": [
"mail_forward_email",
"mail_send_email"
],
"path": [
"contacts_get_contact",
"files_list",
"mail_forward_email"
],
"edges": [
{
"from": "contacts_get_contact",
"to": "files_list",
"kind": "agent-mediated"
},
{
"from": "files_list",
"to": "mail_forward_email",
"kind": "agent-mediated"
}
],
"wired": false
}
}
],
"toxicFlows": [
{
"id": "flow-1",
"severity": "critical",
"confidence": "strong",
"untrustedInput": [
"contacts_get_contact",
"files_get",
"mail_download_attachment",
"mail_export_email",
"mail_parse_email"
],
"sensitiveSource": [
"files_list"
],
"externalSink": [
"mail_forward_email",
"mail_send_email"
],
"selfContained": false,
"path": [
"contacts_get_contact",
"files_list",
"mail_forward_email"
],
"pathWired": false,
"description": "A cross-tool exfiltration chain exists: contacts_get_contact → files_list → mail_forward_email."
}
],
"capabilities": [
{
"tool": "calendar_list_calendars",
"tags": [],
"reasons": {}
},
{
"tool": "calendar_list_events",
"tags": [],
"reasons": {}
},
{
"tool": "calendar_get_event",
"tags": [],
"reasons": {}
},
{
"tool": "calendar_create_event",
"tags": [],
"reasons": {}
},
{
"tool": "calendar_update_event",
"tags": [],
"reasons": {}
},
{
"tool": "calendar_delete_event",
"tags": [],
"reasons": {}
},
{
"tool": "contacts_list_address_books",
"tags": [],
"reasons": {}
},
{
"tool": "contacts_query_contacts",
"tags": [],
"reasons": {}
},
{
"tool": "contacts_list",
"tags": [],
"reasons": {}
},
{
"tool": "contacts_get_contact",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"fetch\""
]
}
},
{
"tool": "contacts_update_contact",
"tags": [],
"reasons": {}
},
{
"tool": "contacts_delete_contact",
"tags": [],
"reasons": {}
},
{
"tool": "contacts_create_contact",
"tags": [],
"reasons": {}
},
{
"tool": "files_list",
"tags": [
"sensitive-source"
],
"reasons": {
"sensitive-source": [
"keyword \"list_files\""
]
}
},
{
"tool": "files_get",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"download\""
]
}
},
{
"tool": "files_upload",
"tags": [],
"reasons": {}
},
{
"tool": "files_create_folder",
"tags": [],
"reasons": {}
},
{
"tool": "files_delete",
"tags": [],
"reasons": {}
},
{
"tool": "files_move",
"tags": [],
"reasons": {}
},
{
"tool": "mail_move_email",
"tags": [],
"reasons": {}
},
{
"tool": "mail_archive_email",
"tags": [],
"reasons": {}
},
{
"tool": "mail_mark_email_read",
"tags": [],
"reasons": {}
},
{
"tool": "mail_pin_email",
"tags": [],
"reasons": {}
},
{
"tool": "mail_delete_email",
"tags": [],
"reasons": {}
},
{
"tool": "mail_download_attachment",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"download\""
]
}
},
{
"tool": "mail_upload_attachment",
"tags": [],
"reasons": {}
},
{
"tool": "mail_search_emails",
"tags": [],
"reasons": {}
},
{
"tool": "mail_get_recent_emails",
"tags": [],
"reasons": {}
},
{
"tool": "mail_get_email",
"tags": [],
"reasons": {}
},
{
"tool": "mail_export_email",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"download\""
]
}
},
{
"tool": "mail_forward_email",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"forward_email\""
]
}
},
{
"tool": "health_check",
"tags": [],
"reasons": {}
},
{
"tool": "mail_set_identity",
"tags": [],
"reasons": {}
},
{
"tool": "mail_list_identities",
"tags": [],
"reasons": {}
},
{
"tool": "mail_import_email",
"tags": [],
"reasons": {}
},
{
"tool": "mail_manage_email_labels",
"tags": [],
"reasons": {}
},
{
"tool": "mail_list_mailboxes",
"tags": [],
"reasons": {}
},
{
"tool": "mail_create_mailbox",
"tags": [],
"reasons": {}
},
{
"tool": "mail_rename_mailbox",
"tags": [],
"reasons": {}
},
{
"tool": "mail_delete_mailbox",
"tags": [],
"reasons": {}
},
{
"tool": "mail_list_masked_emails",
"tags": [],
"reasons": {}
},
{
"tool": "mail_create_masked_email",
"tags": [],
"reasons": {}
},
{
"tool": "mail_update_masked_email",
"tags": [],
"reasons": {}
},
{
"tool": "mail_parse_email",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"download\""
]
}
},
{
"tool": "mail_reply_to_email",
"tags": [],
"reasons": {}
},
{
"tool": "mail_send_email",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"send_email\""
]
}
},
{
"tool": "mail_search_snippets",
"tags": [],
"reasons": {}
},
{
"tool": "mail_get_email_thread",
"tags": [],
"reasons": {}
}
],
"surfaceDigest": "d72a57cbc8602e68ca611e38994f0d329e82d7117f5f1491f3be91f44adb097b",
"stats": {
"tools": 48,
"prompts": 0,
"resources": 0,
"findingsBySeverity": {
"critical": 1,
"high": 0,
"medium": 0,
"low": 0,
"info": 0
}
}
}