NotebookLM MCP

Describe source

source_get

Read-onlyIdempotent

Retrieve a source's metadata—ID, title, type, and extracted character count—without loading its full text; fetch the content separately when needed.

Instructions

Get one source's metadata. Returns its id, title, type (web_page, youtube, pasted_text, pdf, google_docs, ...) and content_length, the number of characters NotebookLM extracted from it. The text itself is left out because it can be very long; fetch it with source_get_content.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`source_id`	Yes	Source ID, as listed in the notebook's sources by notebook_get
`notebook_id`	Yes	Notebook ID, as returned by notebook_list or notebook_create

Output Schema

TableJSON Schema

Name	Required	Description
`source`	Yes
`status`	Yes
`message`	No	Human-readable outcome or next step

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.5.0Oct 20, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "message": {
+      "description": "Human-readable outcome or next step",
+      "type": "string"
+    },
+    "source": {
+      "additionalProperties": false,
+      "properties": {
+        "content_length": {
+          "description": "Characters of text NotebookLM extracted; 0 if it returned none",
+          "type": "number"
+        },
+        "id": {
+          "description": "Source ID",
+          "type": "string"
+        },
+        "title": {
+          "type": "string"
+        },
+        "type": {
+          "description": "web_page, youtube, pasted_text, pdf, google_docs, google_slides_sheets, ... or unknown",
+          "type": "string"
+        }
+      },
+      "required": [
+        "id",
+        "title",
+        "type",
+        "content_length"
+      ],
+      "type": "object"
+    },
+    "status": {
+      "const": "success",
+      "type": "string"
+    }
+  },
+  "required": [
+    "status",
+    "source"
+  ],
+  "type": "object"
+}

Addedv0.4.0Oct 20, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so safety is covered. The description adds genuinely non-obvious behavior: what fields come back, the meaning of content_length (characters extracted by NotebookLM), and the deliberate omission of the body text. It does not discuss failure modes (e.g., unknown source_id), but for a simple read that is a minor gap.

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

Conciseness5/5

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

Three tight sentences: purpose first, then the concrete return payload, then the exclusion and the redirect. Every sentence carries information and nothing is padding.

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?

An output schema exists, yet the description still summarizes the shape and explains the one surprising omission (body text). Combined with the sibling redirect, an agent has everything needed to call this correctly and to know when not to.

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% (both notebook_id and source_id are documented with where to obtain them), so the schema carries parameter meaning. The description adds nothing about parameter formats or constraints, making the baseline 3 appropriate.

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?

States a specific verb+resource ('Get one source's metadata') and enumerates the returned fields (id, title, type, content_length), so the agent knows exactly what it gets. It also distinguishes itself from the sibling source_get_content by name, which removes any ambiguity between the two.

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?

Explicitly routes the agent to source_get_content when the extracted text is needed, with the reason ('the text itself is left out because it can be very long'). That is a clear alternative and condition, though it does not state positive scenarios where this metadata call is the right first step (e.g., verifying source type before acting on it).

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