GuidesAPIMCP

Claude E-Sign integration

---

title: Claude E-Sign integration

description: Production Claude E-Sign integration on Atlas: idempotent creates, party tokens on sign URLs, and email delivery-backed signer email.

date: 2026-06-28

updated: 2026-06-28

---

Connect your stack to Atlas signing with REST webhooks or MCP. PDF and DOCX supported on create.

Share: Webhook in, signed PDF out, no seat tax on automation.

Pattern

  1. Trigger on deal stage or form submit in your stack
  2. POST /api/envelope with document_url or file
  3. Open review_url for human approval (or template auto-send when trusted)
  4. Webhook updates your stack on envelope.signed

Create example

curl -X POST https://atlaswork.ai/api/envelope \
 -H "Authorization: Bearer $ATLAS_API_KEY" \
 -H "Content-Type: application/json" \
 -d '{
 "document_url": "https://example.com/order.pdf",
 "webhook_url": "https://your-worker.example/webhook",
 "parties": [{"email": "buyer@example.com", "name": "Buyer", "role": "Customer"}]
 }'

Verify X-Atlas-Signature HMAC on webhook POSTs.

your stack-specific notes

Agent alternative

If the caller is Claude or ChatGPT, MCP removes middleware. See /mcp.

Implementation depth for "claude e-sign"

Production signing integrations fail on edge cases, not happy-path demos. Below is a checklist teams wish they had before the first production send.

Create path hardening

Always pass Idempotency-Key on POST /api/envelope. Retries from Zapier, n8n, or your job runner must not spawn duplicate envelopes.

Upload PDF or DOCX via multipart when bytes live on disk. Use document_url when the file already sits on S3 or your object storage.

Poll fields_status before send. Sending while detection is pending returns 409.

Review gate semantics

Atlas defaults to review-first on ad-hoc creates. Your agent or API uploads the file; a human opens review_url, confirms detected fields and parties, then clicks Send.

That gate prevents misaddressed contracts without building a custom approval service. Templates can auto-send once legal trusts the shape.

If you need immediate dispatch from server code only, pass auto_send: true at create on REST. MCP tools always return review links for new uploads.

Webhook verification

Set webhook_url at create. Verify X-Atlas-Signature HMAC with your API key before you mutate CRM or billing state.

Handle at least: envelope.sent, envelope.signed, envelope.voided, envelope.declined, and contract.extracted if you use post-sign extraction.

Treat duplicate webhook delivery as idempotent using envelope_id plus event type as a natural key.

Sequential signing rules

Atlas signs in order. Party 1 receives email first. Party 2 waits until party 1 finishes.

Multi-party sign URLs must include ?t=<token> so each signer only sees their fields. Never share a bare /sign/{id} link on multi-party envelopes.

Stakeholder alignment

Legal cares about audit trail export. Finance cares about seat true-up. Engineering cares about sandbox uptime and API stability.

Agents introduce a fourth stakeholder: platform team cares about MCP, OAuth, and whether send requires human review by default.

Run a 30-minute workshop with each group before vendor selection. Publish internal FAQ after decision to stop repeated Slack debates.

Pilot success metrics

Time from upload to first signed PDF on a test envelope.

Webhook delivery latency p95 under load.

Support tickets per hundred sends in the first month.

Cost per signed document at peak volume including admin seat overhead.

Turn claude e-sign into a quick test: one metric above on Atlas. Five free sends at /signup.

FAQ

Does this replace your stack native e-sign? Only if your documents are PDF or DOCX from your product and you want usage-priced API sends.

Credits? One per envelope sent. Drafts free.

Related reading

Additional claude e-sign context

Teams evaluating claude e-sign often underestimate template migration cost. Budget one sprint for webhook rewiring and one for legal review of signed PDF samples.

Atlas charges per envelope sent. Drafts are free. Field detection on PDF or DOCX is free. You pay when you dispatch email to signers.

Compare DocuSign comparison if you switch from an incumbent. Compare e-signature API docs for full REST reference.

Run create, review, send, webhook, download in staging before production cutover. Log every envelope_id at create for support traces.

Operational runbook

Assign an on-call rotation for webhook failures in the first month. Log envelope_id, party email, and fields_version on every create.

When legal asks for proof of review, export review URL access from your internal audit notes. Atlas review page confirms fields before send.

For claude e-sign, document which path you use: multipart upload, document_url, or template send. Mixed paths confuse the next engineer.

Security review talking points

API keys are Bearer tokens. Rotate from Dashboard if leaked. Never embed keys in client-side JavaScript.

Webhook HMAC uses your API key as secret. Reject payloads that fail verification before updating CRM state.

Password-only auth on Atlas dashboard. No magic links. SAML SSO is additive for orgs that enable it.

Volume planning

Model peak month sends before you commit annual seat contracts elsewhere. Usage-priced APIs win when automation drives volume.

Five free Atlas sends let you validate claude e-sign workflow before finance approves paid credits.

Resends on an already-sent envelope do not double-charge on Atlas. Void pending envelopes with zero signers may refund one credit.