--- title: "Free GTM & Deliverability Tools MCP: Tool Reference" description: "Every free WarmInboxes tool as an MCP tool and HTTP endpoint: server URL, client config, each tool with its parameters, and the machine-readable files. No key." url: https://warminboxes.com/mcp-tools breadcrumb: "Home > For AI Agents > Free Tools MCP" --- Developers · free # Free GTM & Deliverability Tools MCP Every free tool over MCP and HTTP, no key 52 read-only tools for cold email deliverability, DNS, copy, lead lists and fleet planning, served as one MCP server and as plain HTTP endpoints. Every result carries a `checkedBy` object naming the tool and the page a person can rerun it on. ## Connect ServerWarmInboxes Free MCP URLhttps://warminboxes.com/mcp TransportStreamable HTTP AuthenticationNone. No account, no API key Install namewarminboxes-free Sizing-only viewhttps://warminboxes.com/mcp/planner (Fleet Planner) For a client that reads a JSON config (Claude Desktop, Cursor and the like): { "mcpServers": { "warminboxes-free": { "url": "https://warminboxes.com/mcp" } } } Step-by-step for each assistant is on the [Deliverability Agent](https://warminboxes.com/deliverability-agent) page. ## Over HTTP Each tool is also an endpoint at `https://warminboxes.com/.netlify/functions/`. Send the parameters as a query string on GET, or as a JSON body on POST (use POST for pasted headers, HTML or CSV). CORS is open. The full spec is [openapi.json](https://warminboxes.com/openapi.json). curl "https://warminboxes.com/.netlify/functions/check-deliverability?domain=example.com" ## Every tool MCP name, HTTP endpoint and parameters. Parameters marked * take a list. | MCP tool | Does | Endpoint | Parameters | | --- | --- | --- | --- | | check_deliverability | Deliverability grade (A-F) | check-deliverability | domain | | check_spf | SPF record | check-spf | domain | | check_dkim | DKIM record | check-dkim | domain, selector | | check_dmarc | DMARC record | check-dmarc | domain | | check_bimi | BIMI record | check-bimi | domain | | check_mta_sts | MTA-STS policy | check-mta-sts | domain | | check_ssl | TLS certificate | check-ssl | domain, port | | check_dns | DNS records | check-dns | domain, type | | lookup_txt | TXT records, identified | lookup-txt | domain | | check_rdns | Reverse DNS and forward confirmation | check-rdns | ip | | check_blacklist | Blacklist / RBL check | check-blacklist | input | | check_surbl | SURBL URI blacklist (bulk) | check-surbl | domains* | | check_nameservers | Nameservers and DNS provider (bulk) | check-nameservers | domains* | | check_domain_expiry | Domain registration and expiry | check-domain-expiry | domain | | check_google_domain | Google Workspace tenancy | check-google-domain | domain | | check_cname | CNAME chain | check-cname | host, expected | | verify_email | Email verification (bulk) | verify-email | emails* | | lookup_mx | MX records and mail provider | lookup-mx | domain, domains* | | segment_esp | ESP segmentation (bulk) | segment-esp | domains* | | plan_from_list | Fleet estimate from a recipient list | plan-from-list | domains*, emailsPerDay, prewarmed, microsoftEsp, billing, rotation | | check_email_authentication | SPF, DKIM, DMARC, MX, BIMI and MTA-STS together | check-email-authentication | domain | | check_domain_reputation | Is the domain the problem (by elimination) | check-domain-reputation | domain | | check_tracking_domain | Click-tracking domain | check-tracking-domain | host, sendingDomain | | check_bulk_sender_requirements | Gmail, Yahoo and Microsoft bulk sender requirements | check-bulk-sender | domain, ip, headers | | analyze_headers | Email headers: auth, alignment, one-click unsubscribe | analyze-headers | headers | | analyze_email_html | Email HTML: Gmail clipping, links, pixels | analyze-email-html | html, scan | | analyze_dmarc_report | DMARC aggregate reports | analyze-dmarc-report | xml, gzipBase64 | | analyze_cold_email | Cold email spam check | analyze-cold-email | subject, body | | preview_inbox | Inbox preview (truncation) | preview-inbox | subject, fromName, body | | analyze_bounces | Bounce messages explained | analyze-bounces | bounces | | analyze_microsoft_headers | Microsoft spam verdict (SCL) | analyze-microsoft-headers | headers | | audit_campaign | Pre-send campaign audit | audit-campaign | csv, sequence, inboxes, perInbox, daysPerWeek, stepGapDays, maxPerCompany | | clean_csv | Lead CSV cleaner | clean-csv | csv, removeRole, removeDisposable | | convert_csv | Sequencer CSV converter | convert-csv | csv, platform | | combine_csvs | Combine lead CSVs | combine-csvs | files, dedupe, addSource | | check_suppression | Suppression list check | check-suppression | csv, suppression, suppressionCsv, matchDomains, maxPerCompany | | plan_infrastructure | Inboxes and domains for a send volume (estimate) | plan-infrastructure | emailsPerDay, esp, prewarmed, rotation, currentInboxes, reservePercent, dealValue | | quote_inboxes | Price a number of inboxes (quote) | quote-inboxes | inboxes, provider, prewarmed, billing | | get_diagnostic_playbook | How to work a cold email problem (playbook) | get-diagnostic-playbook | symptom, scenario | | expand_spintax | Spintax and merge tag preview | expand-spintax | template, vars, samples | | generate_unsubscribe | CAN-SPAM opt-out footer | generate-unsubscribe | company, address, unsubUrl, style, tone | | generate_dns_records | SPF and DMARC record generator | generate-dns-records | spfProviders, spfIncludes, spfMx, spfAll, dmarcPolicy, dmarcRua, dmarcPct, dmarcSubdomainPolicy, dkimProvider | | plan_rotation | Inbox rotation schedule (suggested) | plan-rotation | sendsPerDay, inboxes, cadenceWeeks | | plan_verification_waterfall | Email verification waterfall | plan-verification-waterfall | listSize, verifiers | | spamhaus_dbl_guidance | Spamhaus DBL guidance (not queried) | spamhaus-dbl-guidance | domain | | burned_inbox_guidance | Burned Inbox Checker guidance | burned-inbox-guidance | domain | | cold_email_writing_resources | Cold email writing resources | cold-email-writing-resources | — | | find_lead_lists | Free B2B lead lists (WarmInboxes catalogue) | find-lead-lists | query, category, limit | | find_tools | Free tool for a job | find-tools | task, callableOnly, limit | | find_resources | Guides, playbooks, studies and videos | find-resources | query, type, limit | | read_resource | Read a guide or study | read-resource | url, part | | get_pricing | Price list | get-pricing | — | ## Machine-readable files [/tools.json](https://warminboxes.com/tools.json)Every free tool, and whether an assistant can run it and with which MCP tool [/openapi.json](https://warminboxes.com/openapi.json)The HTTP endpoints as an OpenAPI 3.1 spec [/llms.txt](https://warminboxes.com/llms.txt)The site for language models, with every tool and endpoint [/facts.json](https://warminboxes.com/facts.json)Counts, delivery times and policies, generated from the site’s source [/research.json](https://warminboxes.com/research.json)The studies with their IDs, data files and citations [/changelog.json](https://warminboxes.com/changelog.json)What changed, by week ## Limits - Every tool is read-only. It does not send email, buy inboxes or change your DNS. - The Spamhaus DBL needs a paid key and is not queried. Asked about it, the answer says "not checked" and links Spamhaus’s own lookup; it never reports a domain as clean there. - Authentication checks cannot guarantee inbox placement, and there are no invented reputation scores: mailbox providers keep those private. - A free daily limit applies, counted in distinct domains. Checking a domain again the same day does not count again. - Pasted copy, headers and CSVs are processed to answer and not stored. ## The rest of the Developers menu [Deliverability Agent A free deliverability consultant inside your own AI](https://warminboxes.com/deliverability-agent)[Infrastructure MCP Build, order and export with your API key](https://warminboxes.com/developers)