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set_metadata

DestructiveIdempotent

Update PDF metadata fields like title, author, subject, and keywords. Handles change-protected files with the owner password and rejects signed PDFs.

Instructions

Set metadata. fields keys: title, author, subject, keywords, creator, producer. Needs the owner password if the PDF forbids changes. Signed PDFs are refused.

Any password argument can be "ask": the user then types it on a local page, so it never passes through the chat.

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": {
      "input_path": "<input_path>",
      "fields": "<fields>"
    },
    "name": "set_metadata"
  }
}

Input Schema

Name	Required	Description	Default
`fields`	Yes
`password`	No
`overwrite`	No
`input_path`	Yes
`output_path`	No

Output Schema

Name	Required	Description	Default
`output`	Yes
`updated`	Yes
`password_protected`	Yes
`user_password_changed`	Yes
`permissions_restricted`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.1.1Nov 12, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "output": {
+      "title": "Output",
+      "type": "string"
+    },
+    "password_protected": {
+      "title": "Password Protected",
+      "type": "boolean"
+    },
+    "permissions_restricted": {
+      "title": "Permissions Restricted",
+      "type": "boolean"
+    },
+    "updated": {
+      "items": {
+        "type": "string"
+      },
+      "title": "Updated",
+      "type": "array"
+    },
+    "user_password_changed": {
+      "title": "User Password Changed",
+      "type": "boolean"
+    }
+  },
+  "required": [
+    "password_protected",
+    "permissions_restricted",
+    "user_password_changed",
+    "output",
+    "updated"
+  ],
+  "title": "SetMetadataResult",
+  "type": "object"
+}

First observedv0.1.0Oct 21, 2026

TDQS

A3.8/5.0

Behavior4/5

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

Annotations already flag destructiveHint=true, idempotentHint=true and readOnlyHint=false, so safety is partly covered. The description adds genuinely new behavioral context: owner-password requirements for locked PDFs, refusal of signed PDFs, and the "ask" sentinel that routes password entry to a local page so secrets never enter the chat — none of which appear in annotations or schema.

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?

Three short sentences, front-loaded with the core action and field list, then escalating to prerequisites and the password mechanism. No filler; only minor awkwardness from the line breaks splitting the field enumeration from the main sentence.

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 destructive write tool the essentials are present: what is modified, what keys are accepted, what blocks execution (signed PDFs, missing owner password), and how to handle sensitive passwords. An output schema exists so return values need not be described, and the remaining gap (overwrite/output_path semantics) is secondary to safe invocation.

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 0%, so the description must carry the burden. It does well on two of five parameters — it enumerates valid keys for the required "fields" object and explains the "password" parameter plus the special "ask" value — but says nothing about "overwrite", "input_path", or "output_path", leaving the mutation/output behavior of those undocumented.

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 opens with a specific verb+resource ("Set metadata") and enumerates the supported field keys (title, author, subject, keywords, creator, producer), so an agent knows exactly what it modifies. It is implicitly the write counterpart of get_metadata, but it never names or contrasts with that sibling explicitly.

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?

Useful conditions are given: an owner password is needed when the PDF forbids changes, and signed PDFs are refused outright. However, there is no explicit when-to-use guidance versus get_metadata, and no statement about how this relates to related tools like flatten_pdf or encrypt_pdf.

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