Proton Mail — 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": "proton-mail-mcp",
"source": {
"kind": "package",
"origin": "proton-mail-mcp"
},
"server": {
"name": "proton-mail-mcp"
}
},
"grade": "A",
"score": {
"score": 96,
"threatScore": 99,
"grade": "A",
"band": "A",
"categorySubtotals": {
"injection": 1.2,
"exfiltration": 0,
"permissions": 0,
"supply-chain": 0,
"network": 0,
"hygiene": 0
},
"vector": [
{
"kind": "threat",
"ruleId": "MTC-INJ-AUTH-2",
"category": "injection",
"severity": "low",
"confidence": "heuristic",
"rawWeight": 3,
"confidenceMult": 0.4,
"diminishingFactor": 1,
"appliedPenalty": 1.2
},
{
"kind": "client",
"term": "capability-exposure",
"level": "moderate",
"label": "capability blast radius (moderate) — client exposure if the model is manipulated",
"appliedPenalty": 3
},
{
"kind": "client",
"term": "verification-discount",
"level": "source",
"label": "publisher verification (provenance) — cryptographic build provenance ties the artifact to its source",
"appliedPenalty": 0
},
{
"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": "moderate",
"reasons": [
"ingests untrusted external content (a prompt-injection entry point)",
"can send data / act on an external service"
],
"tags": [
"external-sink",
"untrusted-input"
]
},
"coverage": {
"level": "source",
"inputs": {
"toolSurface": true,
"implementationSource": true,
"packageMetadata": true,
"liveTransport": false
},
"caveats": [
"Tools were statically extracted from the published source (32 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-005",
"title": "Untrusted input can drive an external action",
"category": "exfiltration",
"severity": "medium",
"confidence": "strong",
"description": "Untrusted-input tools ([forward_email, read_message, list_attachments, download_attachment, mark_all_read]) co-exist with external-action tools ([send_email, reply_email, forward_email]). A prompt injection could cause unwanted external actions, though no direct sensitive-data leak path was found.",
"remediation": "Require confirmation for state-changing/egress actions triggered after processing untrusted content.",
"location": {
"kind": "flow",
"name": "forward_email → send_email"
},
"evidence": "untrusted [forward_email, read_message, list_attachments, download_attachment, mark_all_read] → sinks [send_email, reply_email, forward_email]",
"owasp": "LLM06:2025 Excessive Agency",
"references": [],
"data": {
"untrusted": [
"forward_email",
"read_message",
"list_attachments",
"download_attachment",
"mark_all_read"
],
"sinks": [
"send_email",
"reply_email",
"forward_email"
]
}
},
{
"ruleId": "MTC-INJ-AUTH-2",
"title": "Instruction-override directive",
"category": "injection",
"severity": "low",
"confidence": "heuristic",
"description": "Instruction-override directive detected in the description of tool \"read_message\". Instruction-like content in tool metadata is executed by the model, not the human, and is the primary tool-poisoning vector.",
"remediation": "Tool descriptions should describe behavior, not instruct the assistant. Treat imperative / secrecy / sequencing language in metadata as hostile.",
"location": {
"kind": "tool",
"name": "read_message",
"field": "description"
},
"evidence": "ignore previous instructions",
"owasp": "LLM01:2025 Prompt Injection",
"data": {
"kind": "override"
}
}
],
"toxicFlows": [
{
"id": "flow-1",
"severity": "medium",
"confidence": "strong",
"untrustedInput": [
"forward_email",
"read_message",
"list_attachments",
"download_attachment",
"mark_all_read"
],
"sensitiveSource": [],
"externalSink": [
"send_email",
"reply_email",
"forward_email"
],
"selfContained": false,
"description": "Untrusted input can drive an external action even though no sensitive source is exposed."
}
],
"capabilities": [
{
"tool": "send_email",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"send_email\""
]
}
},
{
"tool": "reply_email",
"tags": [
"external-sink"
],
"reasons": {
"external-sink": [
"keyword \"send_email\""
]
}
},
{
"tool": "reply_all_email",
"tags": [],
"reasons": {}
},
{
"tool": "forward_email",
"tags": [
"untrusted-input",
"external-sink"
],
"reasons": {
"untrusted-input": [
"keyword \"read_message\""
],
"external-sink": [
"keyword \"forward_email\""
]
}
},
{
"tool": "list_folders",
"tags": [],
"reasons": {}
},
{
"tool": "list_messages",
"tags": [],
"reasons": {}
},
{
"tool": "read_message",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"read_message\""
]
}
},
{
"tool": "list_attachments",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"fetch\""
]
}
},
{
"tool": "download_attachment",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"read_message\""
]
}
},
{
"tool": "search_messages",
"tags": [],
"reasons": {}
},
{
"tool": "move_message",
"tags": [],
"reasons": {}
},
{
"tool": "delete_message",
"tags": [],
"reasons": {}
},
{
"tool": "update_message_flags",
"tags": [],
"reasons": {}
},
{
"tool": "get_thread",
"tags": [],
"reasons": {}
},
{
"tool": "mark_all_read",
"tags": [
"untrusted-input"
],
"reasons": {
"untrusted-input": [
"keyword \"read_message\""
]
}
},
{
"tool": "save_draft",
"tags": [],
"reasons": {}
},
{
"tool": "bulk_move",
"tags": [],
"reasons": {}
},
{
"tool": "bulk_delete",
"tags": [],
"reasons": {}
},
{
"tool": "bulk_update_flags",
"tags": [],
"reasons": {}
},
{
"tool": "create_folder",
"tags": [],
"reasons": {}
},
{
"tool": "create_label",
"tags": [],
"reasons": {}
},
{
"tool": "rename_folder",
"tags": [],
"reasons": {}
},
{
"tool": "delete_folder",
"tags": [],
"reasons": {}
},
{
"tool": "update_message_labels",
"tags": [],
"reasons": {}
},
{
"tool": "bulk_update_labels",
"tags": [],
"reasons": {}
},
{
"tool": "empty_folder",
"tags": [],
"reasons": {}
},
{
"tool": "count_messages",
"tags": [],
"reasons": {}
},
{
"tool": "folder_stats",
"tags": [],
"reasons": {}
},
{
"tool": "top_senders",
"tags": [],
"reasons": {}
},
{
"tool": "move_thread",
"tags": [],
"reasons": {}
},
{
"tool": "delete_thread",
"tags": [],
"reasons": {}
},
{
"tool": "flag_thread",
"tags": [],
"reasons": {}
}
],
"surfaceDigest": "328d2c21ad25fe054ab421e2c7e195d745e204f0172825813da0f84f33703da4",
"stats": {
"tools": 32,
"prompts": 0,
"resources": 0,
"findingsBySeverity": {
"critical": 0,
"high": 0,
"medium": 1,
"low": 1,
"info": 0
}
}
}