{"generated_at":"2026-10-14T20:07:22+00:00","item":{"added_at":"2026-07-21","analysis_method":"independent_manual_review_2026-10-10","assessment_status":"provisional","auth_posture":"auth_required","category":"Web Connector","confidence":"medium","description":"PostGrid connects Claude to postal-address verification and direct-mail operations. Build mailing lists, send physical mail, and inspect mailing analytics or tracking. Authenticated API tools can perform writes, including letters, postcards, and checks.","did":"76870959-d9ea-465e-a786-7d1ef6227ddd","documentation_url":"https://guides.postgrid.com/","editorial_description":{"extended_description":"Supported mailings include self-mailers, snap packs, and transactional mail. Discover endpoint schemas, handle uploads, and execute read or write API operations.","schema_version":1,"summary":"PostGrid connects Claude to postal-address verification and direct-mail operations.\nBuild mailing lists, send physical mail, and inspect mailing analytics or tracking.\nAuthenticated API tools can perform writes, including letters, postcards, and checks."},"homepage_url":"","icon":"","id":"76870959-d9ea-465e-a786-7d1ef6227ddd","installs":0,"last_scanned":"","license":"","long_description":"Supported mailings include self-mailers, snap packs, and transactional mail. Discover endpoint schemas, handle uploads, and execute read or write API operations.","manual_assessment":"high","manual_review":{"all_findings":[{"evidence":"The catalogue description identifies PostGrid as sending letters, postcards and checks, while this tool invokes arbitrary described write endpoints.","reasoning":"Sending physical communications/checks is consequential messaging as the user.","risk_type":"messaging_as_user","severity":"high","title":"Generic write calls can send physical mail","triggering_tools_or_skills":["make_write_api_call"]},{"evidence":"Physical mail API operations can incur postage/production charges and checks can move value; endpoint schemas are dynamically selected.","reasoning":"The gateway has a financial High ceiling that is not statically bounded.","risk_type":"financial_transaction","severity":"high","title":"Write calls can create paid mail/check jobs","triggering_tools_or_skills":["make_write_api_call"]},{"evidence":"These tools support durable asset upload for mail jobs.","reasoning":"They write customer documents into the remote service.","risk_type":"file_write","severity":"medium","title":"Creates upload links and accepts uploaded assets","triggering_tools_or_skills":["generate_upload_link","wait_for_upload"]},{"evidence":"The action set depends on a searched external API specification rather than fixed catalogued tools.","reasoning":"The packet cannot enumerate all reachable endpoints or effects.","risk_type":"generic_gateway","severity":"low","title":"API operation surface is discovered and invoked dynamically","triggering_tools_or_skills":["describe_endpoint","search_api_spec","make_read_api_call","make_write_api_call"]}],"assessment_status":"provisional","auth_and_scopes":"Authentication to a PostGrid account/API is required; make_write_api_call accepts dynamically described endpoints whose action and confirmation bounds are not enumerated.","blocked_missing_evidence":"The exact MCP-visible PostGrid endpoint allowlist, schemas, spend/check restrictions, recipient confirmation, idempotency and authorization controls.","confidence":"medium","displayed_risk":"high","evidence_completeness":"insufficient","manual_overall_risk":"high","official_sources":[{"accessed_at":"2026-10-10T20:24:37Z","url_or_path":"plutosecurity/plutonium@b749c8dc43536c794409be9805edd48063f045e2:app/data/conn/claudesec/76870959-d9ea-465e-a786-7d1ef6227ddd.json","what_it_proves":"Candidate PR #125 record identity (name \"PostGrid\", publisher, type web_connector) and 6 stored tool names; no tool descriptions stored"},{"accessed_at":"2026-09-22T10:46:07Z","url_or_path":"https://api.anthropic.com/api/directory/servers?verified_tier=anthropic,partner,community (snapshot claude-directory-all-tiers-2026-09-22.json)","what_it_proves":"Official Claude Directory listing https://claude.ai/directory/76870959-d9ea-465e-a786-7d1ef6227ddd: complete tool_names inventory (6 tools), remote streamable-http endpoint https://mcp.postgrid.com/mcp, auth_posture auth_required, directory tier community"}],"primary_reason":"PostGrid’s dynamic write gateway can send paid physical mail/checks, but its reachable endpoint allowlist and confirmation rules are not statically reviewed.","provisional_risk":null,"publication_recommendation":"fix","requires_runtime_verification":true,"review_key":"claude:76870959-d9ea-465e-a786-7d1ef6227ddd","reviewed_at":"2026-10-10","reviewer_notes":"Reviewed all six wrapper tools. High follows the declared product/action surface; publication should not imply every write endpoint has been individually assessed.","risk_domains":{"arbitrary_network_access":"false","authz_ambiguity":"true","browser_control":"false","credential_or_admin_actions":"false","deletes_data":"false","deployment_or_infrastructure":"false","dynamic_hidden_actions":"true","filesystem_or_repo_access":"true","forwards_data_to_third_party":"true","modifies_data":"true","persistent_credentials":"true","prompt_injection_exposure":"true","provenance_uncertainty":"true","reads_private_data":"true","runs_code_or_queries":"false","sends_messages_as_user":"true","spends_or_moves_money":"true"},"tools_or_skills_reviewed":6,"tools_or_skills_total":6},"name":"PostGrid","needs_runtime_verification":true,"plutonium_url":"https://plutonium.pluto.security/detail.html?planet=claudesec&did=76870959-d9ea-465e-a786-7d1ef6227ddd&utm_source=plutonium_analysis_skill&utm_medium=claude_skill&utm_campaign=connector_risk_assessment","privacy_policy_url":"https://www.postgrid.com/legal/privacy-policy","provisional_risk":null,"publication_recommendation":"fix","publisher":"PostGrid","publisher_url":"https://postgrid.com/","remote_url":"https://mcp.postgrid.com/mcp","repository_url":"","risk":"high","risk_severity":"high","security_risks":[{"description":"This connector can publish or send messages and content using the connected identity. Review findings: Sending physical communications/checks is consequential messaging as the user.","evidence":"Generic write calls can send physical mail: The catalogue description identifies PostGrid as sending letters, postcards and checks, while this tool invokes arbitrary described write endpoints.","manual_risk_type":"messaging_as_user","remediation":{"block_tool_categories":["sends_externally"],"steps":["Require review before messages, posts, or publications are sent.","Restrict delivery to test or internal recipients where possible."]},"risk_type":"sends_messages_as_you","severity":"high","title":"Generic write calls can send physical mail","triggering_tools":["make_write_api_call"]},{"description":"This connector can spend money, consume paid credits, or change financially consequential resources. Review findings: The gateway has a financial High ceiling that is not statically bounded.","evidence":"Write calls can create paid mail/check jobs: Physical mail API operations can incur postage/production charges and checks can move value; endpoint schemas are dynamically selected.","manual_risk_type":"financial_transaction","remediation":{"block_tool_categories":["financial"],"steps":["Set provider-side spending limits and require approval for every financial action.","Use a dedicated low-balance account and review transaction logs."]},"risk_type":"spends_money","severity":"high","title":"Write calls can create paid mail/check jobs","triggering_tools":["make_write_api_call"]},{"description":"This connector can create, change, export, or otherwise write files. Review findings: They write customer documents into the remote service.","evidence":"Creates upload links and accepts uploaded assets: These tools support durable asset upload for mail jobs.","manual_risk_type":"file_write","remediation":{"block_tool_categories":["state_change"],"steps":["Limit file access to a dedicated working directory.","Review generated or modified files before they are shared or executed."]},"risk_type":"filesystem_access","severity":"medium","title":"Creates upload links and accepts uploaded assets","triggering_tools":["generate_upload_link","wait_for_upload"]},{"description":"This connector can execute code, commands, queries, or dynamically selected actions. Review findings: The packet cannot enumerate all reachable endpoints or effects.","evidence":"API operation surface is discovered and invoked dynamically: The action set depends on a searched external API specification rather than fixed catalogued tools.","manual_risk_type":"generic_gateway","remediation":{"block_tool_categories":["code_execution"],"steps":["Run only in a sandbox with least-privilege credentials and strict resource limits.","Disable generic execution gateways unless their reachable action set is fully understood.","Require approval before execution against production systems or sensitive data."]},"risk_type":"runs_code","severity":"low","title":"API operation surface is discovered and invoked dynamically","triggering_tools":["describe_endpoint","search_api_spec","make_read_api_call","make_write_api_call"]}],"signature_status":"unknown","source_code_reviewed":false,"support_url":"support@postgrid.com","tags":["filesystem_access","network_access","oauth_required","runs_code","sends_messages_as_you","spends_money","web_connector"],"tools":[{"description":"","name":"describe_endpoint"},{"description":"","name":"generate_upload_link","risk":{"category":"state_change","level":"medium","recommendation":"Follow the connector-level remediation and require approval for consequential actions.","why":"This connector can create, change, export, or otherwise write files. Review findings: They write customer documents into the remote service."}},{"description":"","name":"make_read_api_call"},{"description":"","name":"make_write_api_call","risk":{"category":"financial","level":"high","recommendation":"Follow the connector-level remediation and require approval for consequential actions.","why":"This connector can spend money, consume paid credits, or change financially consequential resources. Review findings: The gateway has a financial High ceiling that is not statically bounded."}},{"description":"","name":"search_api_spec"},{"description":"","name":"wait_for_upload","risk":{"category":"state_change","level":"medium","recommendation":"Follow the connector-level remediation and require approval for consequential actions.","why":"This connector can create, change, export, or otherwise write files. Review findings: They write customer documents into the remote service."}}],"tools_count":6,"transport":"streamable-http","type":"web_connector","url":"https://claude.ai/directory/76870959-d9ea-465e-a786-7d1ef6227ddd","uuid":"d0cdf457-ac8a-5c59-8994-b161820e02fc","verification_tier":"community","version":""},"query_key":"postgrid","schema_version":1,"status":"match"}