Fast.io

E-Signature

sign

Read-only

Fastio e-signature reads: sign envelopes and sign templates in a workspace, plus document and audit-certificate download URLs. Writes are on sign_manage.

Input Schema

TableJSON Schema

Name	Required	Description
`limit`	No	Pagination limit (max 500).
`action`	Yes	Operation. Use 'describe' for full action reference.
`offset`	No	Pagination offset (default 0).
`document_id`	No	sign-document-*: document OpaqueId.
`envelope_id`	No	sign-*: numeric envelope ID.
`template_id`	No	sign-template-get: template id (30-char base32, `sa` family).
`workspace_id`	No	Workspace ID (19-digit NUMERIC; the document/audit download stream route rejects custom workspace names). Envelopes are workspace-parented.
`display_limit`	No	Max list rows rendered inline (default 10; the full page is still fetched).
`describe_action`	No	With action='describe': return one action's params and notes instead of the action index.
`envelope_status`	No	sign-list: status filter.

Schema Changelog

Changes observed during successful MCP inspections.

Changed16 schema fields changedOct 3, 2026

changedInput schema / properties / action / enum

Previous value: -[
-  "describe",
-  "sign-list",
-  "sign-create",
-  "sign-get",
-  "sign-update",
-  "sign-send",
-  "sign-void",
-  "sign-document-source-download",
-  "sign-document-source-preview",
-  "sign-document-signed-download",
-  "sign-audit-download",
-  "sign-audit-pdf-download",
-  "sign-retry",
-  "dashboard-sign-link",
-  "sign-template-create",
-  "sign-template-list",
-  "sign-template-get",
-  "sign-template-update",
-  "sign-template-delete",
-  "sign-template-instantiate"
-]New value: +[
+  "describe",
+  "sign-list",
+  "sign-get",
+  "sign-document-source-download",
+  "sign-document-source-preview",
+  "sign-document-signed-download",
+  "sign-audit-download",
+  "sign-audit-pdf-download",
+  "sign-template-list",
+  "sign-template-get"
+]

removedInput schema / properties / confirm

Removed value: -{
-  "description": "Confirmation gate ('true'). REQUIRED for sign-send/sign-void; refused without it.",
-  "enum": [
-    "true",
-    "false"
-  ],
-  "type": "string"
-}

changedInput schema / properties / describe_action / description

Previous value: -"When action='describe', narrow the output to ONE action's full params/notes (e.g. 'sign-create'). Omit to get the compact action index."New value: +"With action='describe': return one action's params and notes instead of the action index."

removedInput schema / properties / description

Removed value: -{
-  "description": "sign-template-create/-update: template description (max 1024).",
-  "maxLength": 1024,
-  "type": "string"
-}

removedInput schema / properties / documents

Removed value: -{
-  "description": "sign-create/-update: JSON documents array 1-20 (see note). sign-template-instantiate: JSON array of slot overrides [{document_slot_index, source_node_id, source_version_id?}].",
-  "type": "string"
-}

removedInput schema / properties / expected_version

Removed value: -{
-  "description": "sign-template-update: the `version` you read from sign-template-get (optimistic CAS). A concurrent write returns 409 — re-read and retry.",
-  "maximum": 9007199254740991,
-  "minimum": 1,
-  "type": "integer"
-}

removedInput schema / properties / expires_at

Removed value: -{
-  "description": "sign-create/-update: envelope expiry as a UTC timestamp 'Y-m-d H:i:s UTC' (NOT a day count; omit/null = policy default).",
-  "type": "string"
-}

removedInput schema / properties / fields

Removed value: -{
-  "description": "sign-create/-update: JSON array of field placements (coords 0..1; see note).",
-  "type": "string"
-}

removedInput schema / properties / name

Removed value: -{
-  "description": "sign-create/-update: envelope name (max 255). sign-template-create/-update: template name (REQUIRED on create). sign-template-instantiate: name for the draft envelope (defaults to the template name).",
-  "maxLength": 255,
-  "minLength": 1,
-  "type": "string"
-}

removedInput schema / properties / policy_json

Removed value: -{
-  "description": "sign-create/-update: optional JSON policy {auth_method,...}.",
-  "type": "string"
-}

removedInput schema / properties / reason

Removed value: -{
-  "description": "sign-void: void reason (max 1024).",
-  "maxLength": 1024,
-  "type": "string"
-}

removedInput schema / properties / recipient_bindings

Removed value: -{
-  "description": "sign-template-instantiate: JSON OBJECT keyed by slot_key -> {email, display_name?, auth_method?}. An ARRAY is rejected by the platform.",
-  "type": "string"
-}

removedInput schema / properties / recipients

Removed value: -{
-  "description": "sign-create/-update: JSON recipients array (see note).",
-  "type": "string"
-}

removedInput schema / properties / snapshot

Removed value: -{
-  "description": "sign-template-create/-update: JSON snapshot object {recipient_slots, document_slots, fields, policy}. On update it is a FULL replacement (see note).",
-  "type": "string"
-}

changedInput schema / properties / template_id / description

Previous value: -"sign-template-get/-update/-delete/-instantiate: template id (30-char base32, `sa` family)."New value: +"sign-template-get: template id (30-char base32, `sa` family)."

changedInput schema / properties / workspace_id / description

Previous value: -"Workspace ID. Envelopes are workspace-parented; use the 19-digit NUMERIC workspace ID (the document/audit download stream route rejects custom workspace names)."New value: +"Workspace ID (19-digit NUMERIC; the document/audit download stream route rejects custom workspace names). Envelopes are workspace-parented."

AddedSep 21, 2026

TDQS

A3.6/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safe-read profile is covered and the description's 'reads' is partly redundant. It does add useful context beyond the annotations – that some actions yield document and audit-certificate download URLs and that writes are delegated elsewhere – but discloses nothing about auth needs, rate limits, or return format specifics.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tightly written sentences: the first front-loads the read scope and the second names the write alternative. No filler, and the important routing information is placed early – only slightly terse for a tool with ten parameters and ten actions.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only, ten-parameter tool with full schema coverage and no output schema, the description covers the read/write split and the return categories but does not help an agent choose among the ten actions or explain the 'describe' workflow. Adequate, but a good part of the selection burden rests on the schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents all ten parameters (including the numeric workspace_id constraint and the action enum) and the baseline is 3. The description adds no parameter-level detail beyond what the schema provides.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description names the domain (Fastio e-signature) and enumerates the read resource categories – sign envelopes, sign templates, and document/audit-certificate download URLs – within a workspace, and explicitly routes writes to the sibling sign_manage. It is clear and sibling-differentiating, though 'reads' is a broad category label rather than a single precise verb.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It states a clear condition for use: read operations live here, while 'Writes are on sign_manage', naming the alternative explicitly. It gives no guidance on which of the ten read actions to pick or on ordering (e.g. describe first), leaving that to the schema.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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