Postlyra.app — Telegram posts from AI chats

Preview an auto-signature

preview_signature

Idempotent

Use this when managing post auto-signatures. Enable a public read-only preview link and return its JPEG screenshot. This saves sharing state and may fetch external media. Include the image and preview link using display instructions. Never sends to Telegram.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "signatureId": "<signatureId>"
    },
    "name": "preview_signature"
  }
}

Input Schema

Name	Required	Description	Default
`signatureId`	Yes	Owner-bound signatureId from list_signatures/create_signature.

Output Schema

Name	Required	Description	Default
`text`	No
`title`	No
`locale`	No
`display`	No
`message`	Yes
`richHtml`	No
`signature`	Yes
`updatedAt`	No
`previewUrl`	No
`screenshot`	No
`signatureId`	Yes
`documentJson`	No
`inlineButtons`	No
`screenshotUrl`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed5 schema fields changedOct 29, 2026

addedInput schema / properties / signatureId / description

Added value: +"Owner-bound signatureId from list_signatures/create_signature."

changedOutput schema / properties / display / properties / imageContentIndex / description

Previous value: -"Index of the native image in this response's content array; null when unavailable."New value: +"Native image index in response content; null if unavailable."

changedOutput schema / properties / display / properties / imageMarkdown / description

Previous value: -"Ready-to-use inline image Markdown for the final answer where the host permits remote images. Preserve the leading !."New value: +"Final-answer image Markdown where host allows remote images; keep leading !."

changedOutput schema / properties / display / properties / instruction / description

Previous value: -"How to include the screenshot in the final user-facing answer; a tool-only image or ordinary link is insufficient."New value: +"Screenshot display instructions for the final answer; tool-only images/ordinary links are insufficient."

changedOutput schema / properties / display / properties / suggestedFileName / description

Previous value: -"Filename suggestion for a host-supported attachment made from the returned bytes; not an existing local path."New value: +"Suggested attachment name for returned bytes; not an existing path."

Changed8 schema fields changedOct 13, 2026

removedOutput schema / properties / channelId

Removed value: -{
-  "maxLength": 128,
-  "type": [
-    "string",
-    "null"
-  ]
-}

removedOutput schema / properties / deliveryDocumentJson

Removed value: -{
-  "description": "Composed publication including the selected auto-signature. Edit documentJson, never copy this composition into the post body.",
-  "type": "object"
-}

removedOutput schema / properties / deliveryInlineButtons

Removed value: -{
-  "items": {
-    "anyOf": [
-      {
-        "type": "object"
-      },
-      {
-        "items": {
-          "type": "object"
-        },
-        "type": "array"
-      }
-    ]
-  },
-  "type": "array"
-}

removedOutput schema / properties / draftId

Removed value: -{
-  "maxLength": 128,
-  "minLength": 1,
-  "type": "string"
-}

removedOutput schema / properties / id

Removed value: -{
-  "maxLength": 128,
-  "minLength": 1,
-  "type": "string"
-}

removedOutput schema / properties / signatureSelection

Removed value: -{
-  "additionalProperties": false,
-  "properties": {
-    "mode": {
-      "enum": [
-        "inherit",
-        "none",
-        "custom"
-      ],
-      "type": "string"
-    },
-    "signatureId": {
-      "maxLength": 128,
-      "type": [
-        "string",
-        "null"
-      ]
-    }
-  },
-  "required": [
-    "mode"
-  ],
-  "type": "object"
-}

removedOutput schema / properties / signatureSnapshot

Removed value: -{
-  "type": [
-    "object",
-    "null"
-  ]
-}

removedOutput schema / properties / status

Removed value: -{
-  "maxLength": 64,
-  "type": "string"
-}

AddedOct 9, 2026

TDQS

A4.2/5.0

Behavior5/5

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

The description adds substantial behavioral detail beyond the annotations: it enables a public read-only link, saves sharing state, may fetch external media, returns a JPEG screenshot, and explicitly does not send to Telegram. These details clarify the mutation and open-world behavior signaled by the annotations.

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?

The description is short and front-loads the main action and output. However, the sentence about display instructions is slightly cryptic and the usage sentence is vague, keeping it from being maximally efficient.

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

Completeness5/5

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

For a one-parameter tool with an output schema and annotations covering safety and openness, the description is complete enough. It covers purpose, side effects, output format, and the no-Telegram-send behavior.

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% for the single signatureId parameter, and the description adds no additional parameter meaning. The baseline score of 3 is appropriate when the schema already fully documents the parameter.

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

Purpose5/5

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

The description states a specific verb and resource: enabling a public read-only preview link for a post auto-signature and returning a JPEG screenshot. This clearly distinguishes it from sibling tools like preview_post or get_signature.

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

Usage Guidelines3/5

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

The phrase 'Use this when managing post auto-signatures' gives only broad implied context. It does not specify when to choose this over preview_post or get_signature, nor does it state prerequisites or exclusions.

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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