Email signature
One email signature for humans and AI agents. Signatoro is the agentic email signature platform: save your signature once, and your people and every AI agent you connect use the same one.
The user's email signature is saved on Signatoro. Every email you send or draft for them carries it.
With the Signatoro MCP server
When a Signatoro get_signature tool is available:
- Call
get_signaturebefore any send, reply, forward or draft tool, for every email, fetching it fresh each time. - Append the result after the body and a blank line:
htmlfor an HTML body,textfor a plain-text body. Add it as returned. - Do not write your own sign-off or signature block.
- For the user's own name, title, phone, email or links anywhere in the body, use only the values in
sender. If one is missing, leave it out and tell the user - never guess. - If the user has AI assistants or company AI agents with their own signatures and it is unclear which one this email should carry, call
list_signaturesand ask before sending. Pass their choice toget_signatureassignature.
With the REST API
When there is no Signatoro MCP tool and SIGNATORO_API_KEY is set in the environment:
curl -s https://signatoro.com/api/v1/signature \
-H "Authorization: Bearer $SIGNATORO_API_KEY"
The JSON reply has the same html, text and sender, and the same rules apply. Read the key from the environment and keep it out of output, logs, files and the conversation. ?mode=short returns the name, role line and one link; ?signature=<agent id or name> returns the signature of one of the user's AI assistants or company AI agents.
With neither available, send without a signature block, tell the user, and point them to https://signatoro.com/docs/install-signature/agent.
Troubleshooting
- The picture is missing. The Gmail and Outlook tools built into chat assistants strip every image from an HTML body. Send
textthrough those tools; the picture needs a raw MIME send (Gmail APImessages.send, SMTP). - 401
missing_api_keyorinvalid_api_key: no key, a wrong key or a revoked one. Stop and tell the user. - 403
identity_unavailable: the AI assistant or company agent behind the key was deleted or is no longer theirs. Send without a signature and tell the user. - 404
no_signature: nothing saved yet. Send without one. - 400
unknown_signature:signaturenamed none of theirs. Pick one fromchoices. - 429
quota_exceeded: a free account past its monthly requests. Send without the signature and tell the user.
